Constantly Adding Balance Chemicals--Is This Normal?

[BikerBill]

Background: 22,500 gallon fresh water inground gunite pool with pebble/plaster finish, Pentair WhisperFlo pump with 1.5 HP motor, Pentair vertical grid FNSP60 D. E. filter, Nature2 G sanitizer, Pentair 320 inline chlorine feeder, and AquaCal AeroTemp heat pump all located 30 miles north of Boston

This pool is 4 years old. I use the hockey puck size trichlor tablets. I try to maintain the free chlorine level at 1 to 1.5 ppm. Since we do have a mineral sanitizer I tried keeping the chlorine at 0.5 to 1.0 but felt I just didn’t have enough margin during hot spells so this year I’ve been keeping the chlorine level a little higher to prevent algae blooms. I test regularly with a Taylor DPD K-2005 test kit.

I notice that the total alkalinity level is always dropping (I try to maintain 100 - 120 ppm). I did some internet searching and found that trichloro-s-triazinetrione lowers alkalinity. So I add sodium bicarbonate to compensate. Based on some additional internet searching I see that sodium bicarbonate has a pH of 8.4 so it raises pH. As the pH goes up I add sodium bisulfate to keep it at 7.4 - 7.6. I swear I end up spending more on balance chemicals than on chlorine tabs. I’m sure by weight I add more sodium bicarbonate than trichlor.

Is this really the way the cycle goes? Add trichlor. Trichlor lowers TA. Add sodium bicarb to raise TA. Sodium bicarb raises pH. Add sodium bisulfate to lower pH. This just doesn’t seem right. It’s hard to believe after a few hundred years of pool chemistry this is the best chemical regimen for residential pools.

If this really is the state of modern pool chemistry, I’d like to determine how much sodium bicarb I need to add to keep things balanced. In other words, if I add 1 pound of trichlor, how much sodium bicarbonate will I need to add? And if I add that much sodium bicarb, how much sodium bisulfate will I need? If I must constantly be adding sodium bicarbonate and sodium bisulfate I’d like to work out a schedule whereby I just add the proper amounts every week or two.

I should mention that the pool water is crystal clear and has been all this season.

I also did some research on the pH of our rainfall. During summer most of our rain comes from the west, including the fossil fuel power plant rich Ohio valley. That rain is quite acidic (pH values of high 4’s to mid 5’s). So I would expect the pH to drift lower due to rain fall. But I never, ever, ever have to add pH plus chemicals. If we do happen to get a summer Nor’easter (not common) then the pH is closer to neutral but still acidic. So the vast majority of our rainfall while the pool is open is fairly acidic.

 

[Leebo]

I notice that the total alkalinity level is always dropping (I try to maintain 100 - 120 ppm). I did some internet searching and found that trichloro-s-triazinetrione lowers alkalinity. So I add sodium bicarbonate to compensate. Based on some additional internet searching I see that sodium bicarbonate has a pH of 8.4 so it raises pH. As the pH goes up I add sodium bisulfate to keep it at 7.4 - 7.6. I swear I end up spending more on balance chemicals than on chlorine tabs. I’m sure by weight I add more sodium bicarbonate than trichlor.

There is a better way to avoid the majority of those issues. Liquid Chlorine. Sure, you'll need to test daily and add more often, but the PH issues, TA issues, and the CYA issues you'll soon run into are almost all avoided. It's funny that the vast majority of the US uses pucks for their chlorine, while a HUGE amount of the rest of the world all use either liquid bleach or SWG for their chlorine. Maybe they're onto something.

 

[schertzy82]

The pool store would certainly have you believe that this cycle is normal so you keep going back to them for more chemicals. But it doesn't have to be that way. Try replacing those pucks with bleach or liquid chlorine (bleach is cheaper) and read pool school on this site to learn the BBB method. Also, if you keep using those pucks, your CYA will continue to rise to a point where your chlorine is ineffective and you'll have to do a partial drain and refill. If you like the convenience of pucks and don't want to manually add chlorine everyday, then maybe a salt water generator would suit you well.

 

[fast1971chevelle]

Very well said shertzy82

 

[MNPoolDreamer]

The bleach certainly helps prevent ph issues, so I agree with making a switch. Adding bleach is probably less work than all the monkeying around you do now.

Are you adding fill water? Could that be affecting your balance?

I used to mess with my water all the time, but when I started to leave it alone, it found a balance.

Hope you can start bbb and enjoying your pool.

 

[BikerBill]

Thanks to all those who responded. To answer MNPoolDreamer's question, I have not added any make-up water this season--Mother Nature has been doing that for me! I read the BBB approach to pool maintenance.

Many years ago we had another pool, an inground vinyl lined pool. We used pucks and had the issue of the CYA level getting too high and binding up the chlorine. So I switched to bleach. But then our total dissolved solids number got too high (I don't recall the value). I was told that bleach was the cause of the high TDS. This was before the internet so information and help were not as easy to come by as they are today. So let me ask all of you bleach users: does bleach result in too much TDS? As I recall the fix for high TDS is the same as it is for too much CYA: partially drain and refill the pool. Ugghhh!

Before sending this response I did some internet searching and see that virtually all pool chemicals add TDS. I see conflicting views on just how much TDS bleach adds. I'm most interested in people's real world experience. So if you've been using bleach for a number of years I'd like to know if TDS is an issue.

 

[Leebo]

Here's a quote from a very smart person.

With chlorinating liquid or bleach, for every 10 ppm FC it will increase salt levels (and TDS) by 17 ppm. So with 2 ppm FC per day chlorine usage over a 6 month swim season that's an increase of around 600 ppm (100 ppm per month) so after 3 years and with some chlorine used in the winter that can be around 2000 ppm. What the pool store failed to tell you is that Trichlor would still increase the salt though at half that rate, but it would also increase the CYA as well (i.e. salt at 50 ppm per month but CYA at 36 ppm per month) and that is much more problematic (over 200 ppm CYA increase in 6 months).

Do you have any summer or winter rains that can overflow the pool to dilute it? That's what I do each winter and after 9 years it keeps my TDS between 1000 and 1500 ppm. I agree that higher TDS levels aren't a problem, but over many years if there is NO dilution at all then one could get far higher than the 3000 ppm salt pools where corrosion issues could be of greater concern. Dilution also reduces the level of any organic chemicals that chlorine doesn't completely oxidize and that don't get caught in the filter.

Keep in mind the salt levels that users of a SWG keep in their pool. Do they run into with cloudy water all the time?? The TDS does have SOME merit...but if all items of the TDS are kept in check you will not have issues with your TDS levels. Ignore the pool store!

 

[JasonLion]

TDS has no merit what so ever. It is an old misunderstanding from before people understood how CYA worked and didn't have a CYA test, so they used TDS as a proxy for CYA. Far better to measure CYA directly and completely ignore TDS. The problem with TDS is that you have no idea which chemicals are involved in causing the level. Many of them are just fine, others are problematic. It is far far better to just measure the problematic ones directly and ignore TDS, which really tells you nothing.

Also, the whole "bleach increases TDS more quickly" story, while having a very small kernel of truth, was invented solely for the purpose of bad mouthing bleach to prevent customers from purchasing chlorine at the grocery store, to help pool stores keep their customers. Bleach does increase TDS just a little tiny bit quicker, but the specific chemicals bleach adds (mostly salt) are harmless and can be completely ignored. SWG pools with added salt are just fine, and bleach will never add as much salt as is used in a SWG pool.

 

[BoDarville]

Before sending this response I did some internet searching and see that virtually all pool chemicals add TDS. I see conflicting views on just how much TDS bleach adds. I'm most interested in people's real world experience. So if you've been using bleach for a number of years I'd like to know if TDS is an issue.

TDS consists of several elements, but the big three are salt, CH, and CYA. TDS is basically meaningless by itself. You will notice that among the recommended test kits, none of them include a test for TDS by design. You need to test the individual levels. For example, a TDS of 500 could consist of:

• 1. Salt of 470 ppm and CYA of 30 ppm - fine for a non-SWG pool, but (very) low salt and CYA for a SWG pool.

• 2. Salt of 300 ppm and CYA of 200 ppm - The high CYA of 200 is problematic for both non-SWG and SWG pools and will result in a partial drain & refill.

Granted, the above example is greatly simplified. However, it illustrates the point that a TDS reading by itself is rather useless.

BTW, all forms of chlorine add salt to varying degrees (see bottom of Pool Calculator). In addition to salt, some types of chlorine also add CYA (dichlor & trichlor) and CH (CalHypo).

 

[BikerBill]

OK, this is very helpful. I was always a little suspicious of the “don’t use bleach ‘cause it’s full of dissolved solids” line from the pool supply places. They made it sound like these solids were impurities, not fundamental components of the actual chemicals themselves. This was back in the 1980’s. I ended up using 5 gallon carboys of sodium hypochlorite for a while. That worked fine until I got a carboy with a leaky cap that caused some damage to the carpeting in my car’s trunk. I guess I need to do a cost/convenience analysis comparing household bleach in gallons from the supermarket and 1 gallon jugs and 5 gallon carboys of liquid chlorine from a pool place.

Leebo’s quote from chem geek gets me closer to where I really want to go. I’d like to understand what my total chemical usage (TA up, pH down, etc.) and cost for a 3.5 month season would be using trichlor pucks and sodium hypochlorite liquid. It seems that liquid chlorine is a pretty clean option, but it has some inconveniences associated with it. I understand the downside imposed by trichlor regarding CYA. But every year when I close the pool for winter I draw down the water level by at least 16”, probably more like 18”. I calculate that a 16” draw down equates to 6435 gallons or 29% of our 22,500 gallon pool. The Pool Calculator says that would take CYA from 55 to 40 ppm. I still probably end up with increasing CYA for a one year period. But maybe I use liquid chlorine one year and trichlor pucks the next. I guess I need to keep careful track of my chlorine usage since that’s the starting point for understanding this.

This pool is equipped with a mineral sanitizer, a Nature 2 G unit. As I recall it’s a copper/silver ion system. Do these things really work? Can I really safely run at significantly reduced chlorine levels?

And speaking of CYA levels, is there a reliable test? Last year I brought water samples to two different pool places one day apart. One said our CYA was 30 ppm, the other said 92 ppm. That’s really helpful. The test that’s part of my Talylor kit also seems a bit hokey. As I recall you pour a cloudy liquid solution into a test tube until a black target at the bottom of the tube disappears.

Thanks again to who all have responded to my questions!

 

[BoDarville]

And speaking of CYA levels, is there a reliable test? Last year I brought water samples to two different pool places one day apart. One said our CYA was 30 ppm, the other said 92 ppm.

A classic example of why you should trust your test results over the pool store's. I have had similar experiences in the past before I learned this.

The CYA test that comes with any of the recommended kits are the most accurate available to the residential pool owner short of access to professional lab equipment. However, it is one of the more subjective tests and one that is dependent on proper lighting.
Try following the directions here: http://www.troublefreepool.com/extended-test-kit-directions-t25081.html - scroll about 1/2 way down the page until you reach the CYA - Cyanuric Acid section.

When doing this test, I use a best "3 out of 5", meaning I pour the sample into the tube several times until I get 3 consistent readings. I record that reading.

 

[coffeegoddss]

This pool is equipped with a mineral sanitizer, a Nature 2 G unit. As I recall it’s a copper/silver ion system. Do these things really work? Can I really safely run at significantly reduced chlorine levels?

I asked this earlier this year. And, based on last year's experience and the answers I've gotten here, I've decided that the Nature 2 is a waste of money. It really doesn't do anything but add metals to the water. I definately feel better about having a FC level of 5-7 KNOWING that my water is in balance, than hoping it's working at .5 or 1. We had more problems last year due to high CYA from pucks and low FC because of what we believed the Nature 2 was doing for us. I do still have ours hooked up - the zpak cartridge is nice for vacations!!