Low pH with High Alkalinity and Few Options

[csever82]

This is my first post here, so please bear with me. Under the guidance of a licensed pool operator, I take care of the in-ground pool for the townhouse community I live in. Last year, I only had to deal with the chemicals while the regular operator was out of town...the rest of the time, I just plugged in the vacuum and locked up the pool area every night.

Now I have been "promoted" to taking care of the pool alone every day. Although the water looks great most of the time, I have learned quickly that accurate chemical adjustments are really vital vs. the method I was taught. Basically, I was shown how to do things in nondescript quantities like buckets, scoops, and bottles rather than ounces or pounds.

Problem: High-ish total alkalinity with constantly dropping pH and limited options for correction.

Here are my test results from this morning using a Taylor K-2006 kit:
FC: 3.0
TC: About 4.0
pH: 7.0
TA: 190
CH: 225
CYA: Unknown

My pool: 40 x 20 feet, average depth 4.5 feet, plaster
Pool chemicals: Combination of chlorine pucks and granular chlorine, soda ash, cyanuric acid
My pump & filter: Pump has a deep end skimmer, shallow end skimmer, and two main drains; sand filter
Other info: Pool has a flow rate of only about 85 or 90, which is low from what I've been told, but that's because the pump from a previous, smaller pool was salvaged and used on this one. I live in Minnesota, so the pool is open generally Memorial Day weekend through mid-September. The pool is heated to 82°F. It is used heavily every day unless it's raining and/or the air temp is maybe less than 70°F - so in other words, it is rare to find it has not been used heavily all day long. The pool is open 12 hours each day, from 9 a.m. to 9 p.m.

Basically, I used about 10 lbs. of cyanuric acid to lower the TA, which started out at about 220. But it only came down to 190. Meanwhile, the pH drops continuously. I have already used an entire 30-pound bag of soda ash just to keep it at 7.0 to 7.2, and the pool has only been open for a week and a half.

I have read conflicting information regarding the TA as it relates to pH. Some say my TA is high but not high enough to worry about, and one of these people is the guy who "taught" me how to take care of the pool...and he's in charge of ordering the chemicals. He says the acid to lower TA is too expensive to get too much of it, but most of the information I've read indicates that if I can get the TA under control, my pH won't keep declining all the time. I also have no way (that has been provided to me, anyway) to aerate the pool, and I can't find anything in our complex's shop that would help me do so.

So my question is this: should I take up the issue with the property manager directly and just let her know that I need this stuff in order to get everything correct in the pool, or should I just keep going through what seems like large amounts of soda ash to constantly correct the pH? Is my TA too high? Or high but not bad? Also, on a side note, does anyone have any tricks for fixing slightly cloudy water quickly? Usually, the pumps fix that overnight, but once in a while, it's like they can't quite keep up with the bather load or something. The water doesn't turn into milk, but occasionally I can't see the drains really clearly...and I prefer the water to be clear enough to see them from the shallow end. Is time the only solution there (closing the pool for a day every couple weeks or something)?

Please help!!

 

[JasonLion]

Welcome to TFP!

You should never use cyanuric acid to lower either PH or TA. First, it will only lower the PH/TA a little, and second it will raise your CYA level, which you almost certainly do not want. Use either muriatic acid or dry acid (sodium bisulfate). Muriatic acid is preferred, as it doesn't add anything that could possibly be a problem, while dry acid will eventually raise the sulfate level which can be a minor problem in some cases. Muriatic acid is also quite inexpensive.

Both trichlor tablets and the most common form of granular chlorine (dichlor) are extremely acidic, if you are using either one you must constantly raise the PH with soda ash (or borax). Worse, the both add CYA to the water. When your CYA level gets too high you chlorine becomes less and less effective, and trouble generally follows. If what you wrote is all correct, I expect that your CYA level is already off the charts too high, though there is no way to know without testing it.

Given that you are using trichlor, your TA is fine. If you stop using trichlor you will want TA lower.

 

[csever82]

Thanks! CYA is what the other guy had labeled in the shed as ALK minus, and it's what he told me to use. I guess he either learned a long time ago or wasn't paying attention in class...maybe both...

Now...please bear with me again. Some of these questions may seem kind of dumb, but I want to make sure I'm doing this right.

From what I've read through so far, I'm thinking of possibly discontinuing the trichlor and dichlor and going with bleach. Honestly, I know this may sound dumb, but before I got to this site, I never knew that you could actually just add bleach to a pool. Is it common for newbies to think you have to get the fancy, expensive stuff?

I will test the CYA level tonight when I go to close the pool and post the update. Also, if I want to stop using the trichlor, do I just let the feeder tube run out, or turn the flow knob to zero, or both? I realize this is not something that will be corrected overnight, but since this is a community pool, I would like to do this in a way that is least disruptive to residents. In other words, I don't want to close the pool down for a day or two if it is not necessary.

Aside from the CYA level, is there anything I have listed that would indicate, in your opinions, that I need to close it for more than 12 hours at one time at this point?

 

[frogabog]

I would say right now, with your combined chlorine at 1ppm that you need to begin shocking the pool. Shocking isn't a 1 time or even a 12 hour shutdown event but rather a process that has an indeterminate end. It could take a day, it could take a week or more. It depends largely on your ability to maintain shock level beginning to end by testing regularly (hourly at first) and re-dosing with chlorine (bleach) depending on the test results.

Read up in pool school (top of page, right side) and pay particular attention to the "ABC's of Water Chemistry" and "How to shock your pool" sections. Following the guidelines contained within is actually quite important and can make or break your time frame (i.e. - cutting corners or not maintaining shock level the entire time will lengthen the shock process. One step forward... two steps back so to speak).

Once you know the CYA level and post current full test results we'll be better able to recommend solutions. Almost always, if not always, discontinuing trichlor and dichlor is recommended. Chances are your CYA is very high already, and the only way to reduce it (outside of reverse osmosis) is to drain and refill.

I'm pretty sure you can discontinue using trichlor by shutting the feeder down to 0 but make sure you're on board with the required chlorine level you'll have to add manually (bleach) every day which is dependent on your CYA level. With it being a community pool, your bather load will also vary so you'll want to schedule some testing throughout the day while it's in use to make sure it is always above the minimum level for your CYA level. Because you're going to be doing BBB, a few weeks of serious monitoring will be necessary before you'll have a good idea of how much chlorine you'll need each day. I'd also monitor the amount of people using the pool at any given time. If you normally have 4-5 people in the pool at any given time throughout the day and it uses x ppm of chlorine on average per day with this capacity, should a gaggle of 20 teenagers decide to come for a party one afternoon, you'll want to know how that increased load will increase your demand and make sure someone is available to prepare/test/dose accordingly.

Not having chlorine automatically being pumped into the pool at all times does have it's disadvantages when it's a community pool but it doesn't mean you can't go BBB. It'll just take some time to learn how your pool works with varying bather loads.

I do think you need to get a new "you from last year" so you have some help with this. Someone who is there and can test/dose if needed when you're not available. Someone who is on board with BBB. A teen from the neighborhood perhaps?

 

[BoDarville]

csever82:

As a fellow newbie to the forum, welcome aboard! I'm new to the forum but have been practicing BBB for almost a year. On to your questions...

Yes, it is common for many pool owners (not just newbies) to think you need all sorts of fancy chemicals to maintain your pool. We entertain frequently and I have been told several times that I have the cleanest pool they have ever seen. When I tell them my primary source of chlorination is liquid bleach, I either get blank stares or they state that it has to be more than that.

From your FC/TC test results, you are on the cusp of needing to shock. Problem is, until you know your CYA level, you do not know how much chlorine to add to bring the FC up to shock level. CYA is a determining factor in your shock level. Upon testing the CYA level and you find it is high (say 90 or greater), you may need to do a partial drain & refill before you shock. If you perform a drain & refill, you will need to retest your CYA again to determine your shock level and how much chlorine you need to add to bring the FC up to shock level. If I were either shocking or doing a partial drain/refill, I would close the pool until I had completed either or both tasks. Two resources to help you out are:

• 1. Pool School's How to Shock article at http://www.troublefreepool.com/pool-school/shocking_your_pool

• 2. The Pool Calculator at http://poolcalculator.com/. Note that the items in the left-most column (e.g., FC, pH, CYA, etc.) are hyperlinks that you can click to get more information about that item including why you need to test for it.

As for what to do with your trichlor pucks in the feeder, I would either use them up or take them out completely. Leaving them in there and setting the flow knob to 0 runs the risk of accelerating wear on the feeder itself and/or seals since the pucks are now trapped. They still would give off gas and/or result in an abnormally high level of chlorinated water which could get trapped in the feeder. I replaced the cap, seals, and several fittings on the feeder due to excessive wear/tear/leaks caused by chemical erosion when I took ownership of the pool since the previous owner was regular trichlor user.

 

[csever82]

Yeah, I was assuming that (contingent upon the CYA test) I might have to partially drain and refill. I will have to look up the procedure for all of that since the other guy did the actual opening of the pool to begin with this year. If I find that it's necessary to do that, I will just tell the property manager what I'm doing and why. She completely trusts me, so I know she'll be fine with whatever I need to do.

When I test this evening, I will also test my source water and post those results. All I know is that our city just built a new plant a couple years ago.

If I do a partial drain, fill and shock, I will probably do so over the weekend even though that might inconvenience more people...it's just that I'm more available (and so are others) to test the water more often and keep up with everything.

Maybe when it's all over I'll ask for a raise (more credit on my rent, in this case).

 

[linen]

Welcome to tfp, csever82

Us Minnesotans are taking over

First and foremost, you are going to need to know your CYA level to know your next move.

From you test results, it looks like your CC level is about 1 ppm. TC=FC-CC. With a CC level of 1 ppm that is usually a sign that the shock process is needed, though with your high bather load, I suppose that CC level could be temporary.

I do not have experience with a "public" pool, but unfortunately the shocking process can take it's own time...i.e. it's done when it's done. You can help make it most efficient by being prepared to dose every hour and keep the level at or slightly above the FC shock level (for your cya level) which means you will need to keep the pool closed, and you won't know when exactly to tell people it will be back open.

I know you pool isn't totally green, but this post is a good read when you are trying to clear organics: http://www.troublefreepool.com/turning-your-green-swamp-back-into-a-sparkling-oasis-t4147.html

 

[csever82]

I think I must have made a typo before, hence the confusion over needing to shock. My FC and TC are always the same. If there is any change in the test colors, it's undetectable. OK, so here are my test results from last night:
FC: 3.0
TC: 3.0 (no color change from FC test)
pH: 7.0
TA: 200
CH: 220
CYA: Only made it about halfway up to the 100 mark before the dot disappeared, so I'm guessing between 150 and 200.

Because the other guy (the one who gets the supplies) knew I needed more soda ash, he got some and left it for me with some other stuff...namely a huge bag of calcium chloride. He left a note on it saying, "Add the entire bag of calcium tonight and then test hardness again in the morning - this should help balance the pH."

Although I don't know whether that really will help, I went ahead with it because for now, until I get this figured out on my own, I need to at least hope he knows a little bit about what he's saying.

As we all discussed yesterday, my CYA level is through the roof. Here I was doing the test, and the black dot disappeared pretty quickly, so I thought (for whatever reason) that that was a good thing...and then I looked at the levels on the back of the tube. So it made it halfway from the bottom of the tube up to the 100 mark, and based on how far apart the other markings are spaced, I would guess my CYA is between 150 and 200...probably closer to the 150 end. Obviously that's still off the charts.

You were all so helpful yesterday, and from my new understanding, the only way to get the CYA level down is to partially drain and refill. According to the Pool Calculator, I would need to replace about 70% of the water. I realize this is not all going to happen in one day. And although I realized I do not need to shock the pool at this point, I know I will have to after I drain and refill.

And as promised, here are the results from my fill water:
FC: Very low but I expected that! Does change color somewhat, though.
TA: 150
pH: 8.0 or more (I believe it's higher than that)
CH: 180

Alright, now how do I delicately (or not so delicately) mention the subject of closing the pool to drain 70% of the water, refill, and shock? I'm thinking I should just pull the property manager aside and tell her that I've been doing some research, and this is really the only way to fix the problem. She trusts me probably more than she trusts the other guy, and I'm beginning to see why, so I'm sure I'll have her blessing.

Also, with draining such a large percentage of the water, I assume I should do it in increments of maybe 20 or 25%...does that sound right? Assuming I close down the pool entirely for the duration of getting all this in line (including shocking), how long should this all take. It may be worth noting that I am filling the pool with a garden hose.

On the plus side of all this, getting mostly new water in the pool sounds like a great time to stop using the trichlor and dichlor and move to BBB...

 

[csever82]

New readings from this morning after adding the huge bag of calcium:
FC: 3.0
TC: 3.0 (no color change from FC test)
pH: 7.0
TA: 200
CH: 370
CYA: Only made it about halfway up to the 100 mark before the dot disappeared, so I'm guessing between 150 and 200.

The good news is that the pH, although low, didn't seem to go any lower. Also, the FC level held overnight. The pool water was substantially more clear this morning, too...almost as crystal clear as I like it, but not quite.

So it looks like the CYA is the big culprit here. Any further advise would be greatly appreciated!

 

[Isaac-1]

You are basically right on the drain and refill for CYA, the only other option is professional reverse osmosis treatment, which only tends to be available in places with water restrictions, and naturally high CH levels (the southwest mostly). You don't want to drain more than about 25% of the pool water at a time for safety reasons, however there are techniques you can try to minimize the impact of this, like water bagging, or using a large plastic sheet to seperate the ends of the pool, drain from one end while adding water to the other letting the plastic sheet be a baricade between the CYA free fill water and the high CYA pool water. As to how long it will take, a lot depends on your water pressure and how fast the hose will fill it back up, or if you can get more than one hose in there.

Ike

p.s. you may want to dilute a sample down 1:1 with CYA free tap water and redo the CYA test multiplying your result by 2, this helps at extreme off the charts levels to tell how far off the chart you are.

 

[JasonLion]

The guy who is giving you advice has been dramatically wrong a couple of times now. Calcium chloride will not have any effect on PH. If you want to raise the PH add soda ash. If you want to slow the rate at which PH falls add borates.

Your CYA level is also way way too high. The common CYA test will read any CYA level above 100 as 100, so your current CYA level could be just about anything. Given your very high CYA level, your FC level is nowhere near high enough. Regardless, you need to get CYA down to something more reasonable.

If your water rates are reasonably low the simplest thing to do is to drain and fill at the same time. That will end up using more water, but goes more quickly and doesn't get in the way of swimmers as much.

 

[BoDarville]

As for how to broach the subject of draining & refilling 70% of the water with your property manager, you could start by stating that some health departments limit CYA to less than 100 ppm in public pools and 40 ppm or less in public spas (source: http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36). I’m not sure if your townhouse community pool is considered a “public” pool in the eyes of the law, but this guideline should hold weight with your property manager.

As for how to drain the pool, draining and filling at the same time is probably the best & safest bet especially for your situation. If there is any way you can get a second fill hose from another spigot or water source in the on-deck circle, I would do that just in case.

One other thing that may be worth looking into is checking with your water municipality to see if they offer a reduced rate for filling a pool. I would mention that you are doing this for health & sanitation reasons. Being in MN, there is a good chance that they may. Here in TX, not so much with the recent drought.

You are definitely on the right track Keep us posted.

 

[duraleigh]

Summing up, drain/refill your pool until you get your CYA down to around 50. Everything will get better and easier from that point.

 

[csever82]

Re: Low pH, High Alkalinity, High CYA and Few Options

Today's update: more LIES from the other guy. He said, and I quote, "CYA levels aren't important in an outdoor pool."

I went down this morning and the water was pretty cloudy, to the point where I could only barely see the drains, and the deep end is only 6 feet. I told the property manager about the acid level and told her that I've been doing some research, blah blah blah. I told her that, from what I've read (i.e. your advice), the only way to really start fixing all this is to drain and refill in increments. But then the other guy showed up and contradicted everything I said. He said the only answer is continue shocking with more dichlor. But my FC levels are good and holding steady (now around 5, and it holds overnight). So I pushed it. I questioned him. I said, "Chlorine has acid in it, and our chlorine levels are fine. I feel like we need to lower the acid level." That's when he said it was irrelevant in an outdoor pool. I told them that my opinion was that we close the pool until the water at least clears up. Now, I think the water cloudiness has a lot to do with how busy the pool was late yesterday, and usually that clears up overnight fairly well, but not this time. I just feel like closing it for a day and simply letting the pumps run without anyone in there will at least help clear the water.

But, the other guy said it wasn't necessary to close it. And the property manager listened to him. I left kind of disgusted.

Then it got interesting. The property manager came over to my house and asked for my opinion without the other guy present. And I told her my opinion very directly. I said simply that what the other guy is saying is just not true. I expressed my desire to drain most of the water and refill it. She said she is going to talk to one of the owners to make sure that's OK before giving me the green light. I also told her a little about BBB, as it sounds like a much better option for our pool. She was very interested, and like me, never realized you could do all this without need the most expensive chemicals around. I told her (didn't ask - I stated) that if the pool water was this cloudy tonight, I would be shutting down for at least one day to let it clear up. She was fine with that. So now she's going to go talk to the other guy about what he's saying about the acid. She's planning to do it in a manner that doesn't put me in the middle as much - she did run the pool herself many years ago and has forgotten a lot of things, but she can pull out that card. I guess she plans to just say she knows he's wrong about the CYA, and that the only way she knows of to lower it is by partially draining and refilling. What I don't get is why she's dancing around this. I feel like she should just tell the other guy that I'm getting on track, while he derailed long ago, and that she will allow me to call the shots.

Anyway, I don't mean to turn this into a political thread, so back to the subject...

I diluted the test sample today and multiplied the result by 2 for the CYA test to try to get a real reading. And we're at exactly 200. So pool calculator now says to get down to 40, I'd need to replace 80% of the water instead of the 70% I originally estimated. But I suppose at this point, what's another 10%?

I've seen comments saying draining and refilling at the same time would be the safest...what do you mean by that? I know if I planned to keep it open, that's true, but is it unsafe to do it otherwise? I just feel like it would be more straightforward to drain it in increments and then refill it. Any opinion either way?

Thanks for all your help!

 

[chem geek]

The Minnesota Administrative Rules for Pool Water Condition state explicitly in 4717.1750 Subpart 2G

Where a cyanuric acid compound is used to stabilize chlorine, the concentration of cyanuric acid in the pool must not exceed 100 parts per million.

You can look at other rules as well since the Minnesota definition of a public pool that is required to follow these regulations is

A "Public pool" includes any pool, other than a private residential pool operated by any person whether the person is an owner, lessee, operator, or concessionaire. Pools include swimming pools, spa pools (hot tubs), waterparks, plunge pools with flume slides, therapy pools, wave pools, splash pads and interactive water features. Public pools are those located in parks, schools, licensed child care facilities, Home Owners Associations, group homes, motels, camps, resorts, apartment buildings, clubs, condominiums and hotels or any licensed lodging facility.

where the bold emphasis regarding the HOA is mine.

You might show this to the property manager to clearly demonstrate that the other guy does not know what he is talking about.

As for draining and refilling at the same time, you would drain the water from one part of the pool, say from the deep end, and add water from the opposite side of the pool, say from the top of the shallow end. If you do this when the pump is off, then there will be little mixing of the water and the dilution will be more efficient. If on the other hand you do a continuous dilution with the pump on and thoroughly mixing the newly added water into the pool, then replacing 100% volume of the water will only dilute it by 63%.

 

[frogabog]

Bear in mind as well... cloudy water is unsafe water. Not only because it could contain bacteria, but you can't SEE.

Last year a woman died in a public pool and remained submerged for two days while hundreds of people swam in said pool because she couldn't be SEEN. Creepy, and scary.

 

[Thinkly]

I basically think you have two problems in trying to convince the property manager of the proper way to fix your pool water. 1. The other guy. 2. I don't think you understand water chemistry and the BBB method well enough yet to convince anyone. Don't take this wrong because it takes awhile. I have been studying this stuff off and on for 3 yrs and still don't completely understand everything.

Now on to the solution. If you truly want to convince someone of the virtues of the BBB method, let this forum do the talking. Direct your property manager and/or "the other guy" to this site, better yet this thread and let them see for themselves. You can even print this thread out and show it to him/her if that helps.

Regardless, you aren't likely to win this argument on your own, but with the help of the knowledgeable folks here, "the other guy" or any other guy will be quickly shown to be deficient in knowledge.

 

[BoDarville]

csever82:

Sounds like you had quite a discussion with your property manager.

I will begin by bottom-lining the situation: There are several methods of draining/refilling (D&R) a pool, including those discussed on this thread, that will work. I will offer my $0.02 but, at the end of the day, choose a method that you are most comfortable with that works best for your situation given the tools available to you. The biggest risk is delaying action on correcting the CYA situation your pool is faced with.

Chem geek brings up two great points:

1. 1. You officially have the law on your side. I would show your property manager the documentation from the Minnesota Administrative Rules for Pool Water Condition. This will bolster your credibility that you’ve done your homework and know what you are talking about on this issue. I don’t see how your property manager or “the other guy” can argue against this documentation.

• 2. If you drain with the pump on while filling with a hose from the opposite end, there will be more dilution of the new water with the existing water as compared to draining with the pump off, no doubt. Not as big a deal with a CYA of 80-100, but it is a bigger deal given that your retest of CYA is 200. [/list:2ianhkiv]
  
  Bottom line is that you need to replace 80% of your water, or 21,600 of the 27,000 gallons currently in the pool. There are several ways this can be done. Based on your latest test result showing a CYA of 200, here are two alternatives I would consider:
  1. 1. I would begin by draining about 25-50% of the current undiluted water and then add a fill hose at the opposite end of the pool from the drain and continue the drain & refill process until your CYA has dropped sufficiently to cease draining and continue the refill-only process (see below on CYA testing). This approach will get a good chunk of the undiluted existing water out of there while using water more efficiently vs. simultaneous drain/refill from the start with pump on. The pool will need to be closed until the D&R is complete. This approach will require more CYA testing during the D&R process so you know when to cut back on the draining and focus more on refilling, but it has the potential to be more accurate in terms of reaching your target CYA level without undershooting or overshooting it.
  • 2. If you are more comfortable with draining incrementally (partial drain, refill, CYA test, and repeat as necessary) then do that. This method will also necessitate closing the pool.
    
    Any of these methods will get the job done, so do what works best for you. Either way, the sooner you start, the sooner you will be improving the pool. [/list:2ianhkiv]
    
    Regardless of which method you choose, the D&R will be a hands-on process. When doing a simultaneous drain/refill, you will need to monitor the fill rate vs. the drain rate to make sure the water does not get too low. I would go in with the assumption that the drain rate is faster than the refill rate (that’s the case with my pool even with a dedicated fill valve). This means that you will need to check it periodically day & night and make any necessary adjustments to either the drain or refill rate. If possible, I would see if there is any practical way to get a second fill hose.
    
    Make sure you have enough CYA reagent on hand as you will need to perform periodic CYA tests to measure progress during the D&R procedure. Also, make sure there is an adequate amount of chlorine (liquid bleach, right? ) during the D&R process to avoid an algae bloom.
    
    It still may be worth checking with your water municipality to see if they offer a discounted water rate for refilling a pool, especially since you are doing it for health & safety reasons. In MN, there is a good chance that they may offer such a discount. It costs nothing to find out! Either way, your property manager will be impressed that you looked into it

 

[csever82]

All right...drum roll please. After partially draining and refilling the pool over a number of days, here's where we're at:

FC: 4.0
CC: 0
TC: 4.0
pH: 7.4
ALK: 140
CYA: 80
CH: 250

Still not quite there on CYA, but MUCH better than it was, and the pH is not bouncing around nearly as much. I let the remainder of the trichlor pucks in the feeder tube get used up, and haven't refilled it. They had three bottles of bleach hidden in the pool shed, and I used them. I showed the property manager the result, and she asked how I got it looking like this, so I told her. I have her mostly convinced.

And I have attached a picture of the now-sparkling water. Notice how the picture is taken from the shallow end, and you can see the drains in the deep end! :-D

[attachment=0:zgotixkf]Pool Pic 2012.06.13.jpg[/attachment:zgotixkf]

So far, so good.

 

[JasonLion]