Moving from PoolCo to DIY

[mld213]

Hello all,

I've been around the forums for about 10 years, starting when I had to get my mother-in-law's pool in shape for a house sale back in 2012. I appreciate the wealth of knowledge and experience that you all share. Using all the info and methods that you share I turned what had become a fish pond back into a sparkling pool and maintained it myself until the sale. The results were nothing short of fantastic.

Now, I have my own pool and thanks to retirement I now have the time to manage it myself. I'm definitely interested in your advice on how to get from where I am to where I should be.

Background: It's a beautiful pool, built and filled in Sep 2017 (five years ago this month). It has been managed by a pool company (weekly visits) since day-one. They use pucks, of course (automatic feeder on the pump pad). On the "good side", the pool has always sparkled, the water has felt fine, and I’ve never seen a bit of algae. We’ve had some scale on tile at the waterline but nothing bad. They’ve been adding a scale inhibitor and bio guard. There really is no "bad side" that I have yet seen, other than $220/mo. I knew the CYA had to be creeping up and I was guessing that they were keeping FC high but I never tested it myself because the water looked and felt fine.

Now, I am taking over maintenance; I retired and have more time and can do it myself. As I mentioned, I have experience using the TFP method with great results.

I have a DPD kit (Taylor), am a PoolMath subscriber, and have posted results below. I’m pondering my course of action. Clearly these current levels are outside of TFP recommendations.

I expect I could replace a lot of water (half?), cut CYA in half, and make the other adjustments. I’d rather not put myself on the water agency's hit-list during a drought, so I’m wondering if I could wait until the rains come this winter and do it then.

I've tried to include everything pertinent, but if I've missed anything please let me know. Happy to hear your thoughts, recommendations, and suggestions. Many thanks in advance.

Matt

CYA: 120
FC: 23
CC: 0
pH: 7.4
TA: 110
CH: 450
Temp: 87F

Pool Data (in case it doesn't appear in my signature):
45,000 gal, outdoor, in-ground, 20’x46’ (920 sf) PebbleSheen;
Pentair Intelliflo VSF 3.0 hp pump;
Pentair EasyTouch control system;
Pentair Quad DE 100 (100 sf) filter;
Pentair Boost-Rite 1.1 hp boost pump;
Pentair 4-wheel Kreepy Krauly Legend pressure side cleaner;
Solaxx Renaissance UV and Ozone;
Pentair Intellibrite 5G lights
Coverstar automatic electric pool cover;
1 skimmer port / 4 returns / 2 main drains / auto-fill
No multiport valve / No heater/ No spa / Northern California

 

[needsajet]

Interesting! Thanks for the great description.

If it was mine, given the drought and social responsibility aspects, and also the algae-free and sparkly water, I would run the pool as-is, except for planning a switch to a saltwater chlorinator. It's only a matter of time before the CYA becomes unmanageable under the current system, in a low rainfall area. Chlorinating liquid is an option, but just not one that I'd choose myself, especially for a large pool. The CYA will drop over time into a more manageable range. I would keep FC around 10-15 for 120 ppm CYA.

You need to very carefully dilute for testing CYA over 80. I like to use 1 cup (or 250 ml) pool water and 1 cup tap water, stir, and then draw my 7 ml sample from the mixture. You can do it in the test bottle, I know, but that can't be very accurate with such a small quantity.

The gallonage figure sounds a tad high vs. the footprint, so I'd use the chlorinating liquid additions as a way to verify that. (add for FC increase, check FC increase an hour later, repeat 5 or 10 times across a few different jugs of chlorinating liquid)

Be prepared to accept pH at a higher level when the pucks are removed from the system.

You can probably skip all the other pool potions in future.

Welcome to TFP. Good to have you here

 

[flynwill]

I agree that the 45,000 gallon number sounds high, that would imply an average depth o 6.5' for the 08' x 46' pool (But certainly possible if it has a very deep deep end).

Where in NorCal are you? Reverse Osmosis may be an option for getting the CYA back under control without using as much water. But it is not a cheap option.

With warm weather the CYA will degrade slowly if you stop adding more with the TriClor. My salt-water pool looses about 10ppm of CYA per month, so between that and the winter rains (assuming we get winter rains) the CYA might be back to more manageable levels by next spring if you switch to liquid chlorine or an SWG.

 

[mld213]

Interesting! Thanks for the great description.

If it was mine, given the drought and social responsibility aspects, and also the algae-free and sparkly water, I would run the pool as-is, except for planning a switch to a saltwater chlorinator. It's only a matter of time before the CYA becomes unmanageable under the current system, in a low rainfall area. Chlorinating liquid is an option, but just not one that I'd choose myself, especially for a large pool. The CYA will drop over time into a more manageable range. I would keep FC around 10-15 for 120 ppm CYA.

You need to very carefully dilute for testing CYA over 80. I like to use 1 cup (or 250 ml) pool water and 1 cup tap water, stir, and then draw my 7 ml sample from the mixture. You can do it in the test bottle, I know, but that can't be very accurate with such a small quantity.

The gallonage figure sounds a tad high vs. the footprint, so I'd use the chlorinating liquid additions as a way to verify that. (add for FC increase, check FC increase an hour later, repeat 5 or 10 times across a few different jugs of chlorinating liquid)

Be prepared to accept pH at a higher level when the pucks are removed from the system.

You can probably skip all the other pool potions in future.

Welcome to TFP. Good to have you here

Thanks! Yes, within minutes after my post I read about the dilution test for CYA. Don't know why I didn't think of that.

I have a physics background and lots of lab paraphernalia about my shop. So I pulled out some graduated cylinders and precise on the dilution. I did two tests at a 1:2 dilution and got results of 80 and 85. After applying the factor and averaging the results, I think actual CYA is closer to 165. Of course, error range is also doubled, so in the end maybe it's 165 +/-20.

FC is holding at 22. CC is zero. Today will be a heavier than usual swim day (4-6 people) so we'll see what happens.

Your note on my volume seeming a tad higher than footprint is perceptive and astute. We seem to have a deeper than average pool. Four foot shallow end and 9.5 foot deep end. When I calculated the volume I used 1/3 of the length at 4', 1/3 at 9.5' and 1/3 at 6.75' which is a close approximation of the actual profile. I'm pretty sure that somewhere I have the actual profile curve (I measured it before filling--yes, I'm a geek). I suppose I could write an integral and get a more accurate volume, but I think I'll save that assignment for my son when he takes calculus next year.

An SWCG! Yes, yes, I can see that. My sister-in-law has a salt water pool on O'ahu and the water quality is lovely. I admit to being biased, as I grew up in Hawaii and Florida, without a pool, swimming in the ocean. We looked hard at doing salt water for this pool when we built it, but decided not to because we have bluestone decking and were worried about spalling. I did a bunch of anecdotal research at the time and ultimately was left with: "Half of the people say they've had no-problems and the other half say they are having significant problems." So I figured we'd wait and see how we used the pool. Now, I see that our use produces very little splash-out so I wonder if a salt-water pool would be okay. This is probably a topic for its own thread, when the time comes.

Thanks again for the reply and the suggestions.

Matt

 

[mld213]

I agree that the 45,000 gallon number sounds high, that would imply an average depth o 6.5' for the 08' x 46' pool (But certainly possible if it has a very deep deep end).

Where in NorCal are you? Reverse Osmosis may be an option for getting the CYA back under control without using as much water. But it is not a cheap option.

With warm weather the CYA will degrade slowly if you stop adding more with the TriClor. My salt-water pool looses about 10ppm of CYA per month, so between that and the winter rains (assuming we get winter rains) the CYA might be back to more manageable levels by next spring if you switch to liquid chlorine or an SWG.

Thanks for the reply and the data. How do you think it is that you loose 10 ppm of CYA each month? Solely to degradation? I wonder what components CYA degrades into. Does it require sunshine to degrade? (Our cover stays closed most days.) I'm not questioning, just curious and always looking to learn. And I'm certainly not strong in chemistry--I managed to trade a lot of chemistry classes for other science classes. Good to know that CYA will degrade.

I'm in Sonoma County, about 70 miles north of SF.

I thought about RO, but honestly my water is not prohibitively expensive. I have a rural farm and am fortunate to have three sources of water (municipal potable, well, and municipal tertiary). Our well has minerals (iron and manganese) so we use the potable for the pool just to avoid the mineral challenge. I recently heard that we're supposed to get buckets of rain this winter--a "triple Nina"--but that and $3.50 will buy you a cup of coffee (but not the gas to get there).

I expect I'll start looking at SWCG and use whatever rain we get to dilute the existing water (I have a 75 gpm pump so I'll need to watch the forecast this winter and pull some water out of the pool before the rain events).

Re: volume...others have told me we have a deep pool...a 4' shallow end and a 9.5' deep end. Anecdotally, our pool builder said that most people build shallow pools these days; at least not with a very deep end. I can tune up the exact volume calcs. When I filled it, I used a 2" pipe delivering 60 gum and the timing was pretty close to 45,000 gal. I actually have a meter but didn't think to use it at the time.

Thanks again for the reply and info.

 

[needsajet]

With the depth, your volume makes sense; no issue there.

Here's the skinny if you'd like detailed info on the slow degradation of CYA: Degradation of Cyanuric Acid (CYA)

Re: water exchange, I think the most effective way is to wait until your pool water is colder than your source of fresh water, or at least close to the same temperature. You then introduce fresh water slowly onto the surface (for example a hose in the skimmer, fresh water flowing out onto the pool surface) and pump water out using the main drain if it can be isolated, or a small submersible pump. Fresh water floats on the salty pool water, provided it's not significantly colder than the pool water. A non-saltwater pool, after a few years, usually has about 1000 to 1500 ppm salt, enough for a weak halocline to form. It's important that the water be as still as possible while doing the exchange, but you can observe how much has been exchanged by gently sliding the pool brush down the wall. You'll see a shimmer when the brush passes through the transition from fresh water into the salty water.

With CYA that high, it's a practical improvement to get it down to around 80 when you can. It's great that you don't have an algae issue so far.

 

[mld213]

Thanks for the skinny on CYA degradation and on water exchange. Good stuff. I'd not thought about significant levels of salt in my (non-saltwater) pool. I'll grab some reagents and measure. Waiting for pool water to get colder than source definitely means winter here. Even then it may be a challenge but I should be able to get close to parity.

Since the puck feeder is now empty, and I have reasonable access to 10% liquid chlorine, I'll likely use 10% LC and target FC = 20 ppm (15 ppm min) until winter when I can start exchanging water. I'm trying to not change a bunch of variables simultaneously.

I'll use the time to research SWCGs.

Thanks again for all the good info.

 

[needsajet]

If your fill water is sufficiently colder than the pool, you can do the same method from the bottom up. (i.e. fresh water introduced gently to the bottom via e.g. garden hose) while removing water only from the top of the water body.

If you give us the parameters... saltiness of pool, saltiness of fill water, and temperatures of both, we can consult the tables. I'm not sure where to find them here, but have the spreadsheets on my computer, so happy to check for you.

 

[kul]

Yay! Congrats on getting a handle on your pool and ditching the company. I did RO, but there are other methods as noted above to get where you want to be depending on your feels.

 

[newdude]

Lifted from the draining Wiki :

Replacing water in-place process depends on several factors:[4]

• Pool Water TDS (PWTDS)
• Pool Water Temperature (PWT)
• Fill Water TDS (FWTDS)
• Fill Water Temperature (FWT)

DeltaT = (PWT - PWTDS / 165) - (FWT - FWTDS / 165)

If DeltaT is positive, then you want to fill at the lowest point and extract at the surface and at the greatest distance from the lowest point.

If DeltaT is negative, then you want to extract at the lowest point and fill at the surface and at the greatest distance from the lowest point. <-Preferred as it is easier to do with a drain pump and you can fill inside one of the skimmers.

If |DeltaT| < 5, then there will be a lot of mixing.

Salt is the largest component of TDS. No matter what chlorination method you use, salt is added to the pool water and can be significant after many years. Every 1000 ppm of salt is worth about 6F in temperature difference.

Balance the water flow out and in​

Be sure to balance the water out and water in so the pool level stays the same.

When you have the pump you will use, take the effluent hose and fill a 5 gallon bucket while timing it. Calculate your gallons per minute (gpm) from that. Then you can estimate how long to run the process.

It is suggested to exchange 5-10% more water than needed to reduce your CYA/CH/etc to account for errors.

Be sure your pool pump is disabled during this process.

Once started do not stop until complete​

Once started do not stop until you have exchanged the amount of water you wish

 

[mld213]

Needsajet: Thanks, once I get the reagents for salt I'll have a measure for that.
Kul: Thanks for the welcome, I found and read your post on your RO process.
Newdude: Thanks, I'd seen that part of the Wiki, but don't yet have a TDS number.

With no pucks in the feeder, I let FC drop to get a feel for how quickly it would move. FC went from 22 to 18 in three days with a very light swim load. CC stayed at zero. Yesterday (FC = 18) I noticed just an ever so slight murkiness when brushing the walls, so I dumped in 1.75 gallons of 10% LC. FC only went up 1 ppm (from 18 to 19), but the jugs had been on the shelf for a year. I'll put some fresh in today and measure.

pH dropped to 7.2 but I'm going to have 20 Boy Scouts in the pool today so perhaps the aeration will bring it up a bit (if I understand that correctly).

It's been 115 F (46 C) here the past two days; nice to be able to jump in the swim.

 

[newdude]

pH dropped to 7.2

Ph is invalid at 10+ with the block test. Do you have a digital tester ? If not disregard the drops for now.

but I'm going to have 20 Boy Scouts in the pool today

Ammonia eats CYA. I'm not telling you to keep them well hydrated. I'm just sayin.

 

[mld213]

Ph is invalid at 10+ with the block test. Do you have a digital tester ?

Ah, good to know. I have a Hanna pH meter that I use for soil pH tests. I'll pull it out and calibrate it and see what it says.

Ammonia eats CYA. I'm not telling you to keep them well hydrated. I'm just sayin.

Oh, it'll happen, I'm sure! Sharing the joy of the pool makes all the maintenance worth it.

 

[mknauss]

Ammonia eats CYA. I

A bacteria eats the CYA, resulting in ammonia. If left long enough, it transitions to nitrates.

 

[needsajet]

When forced to maintain FC above 10, such as your special circumstances, you can still test pH with the drop-based kit. You have to dilute the sample with distilled water to get the FC down to 10 first. So, for your 18 ppm FC, fill the test vial half-way with pool water, top it up with distilled water, cap the vial and swirl the mixture, then add the pH drops and swirl again. Use only distilled water for this purpose.

 

[mld213]

Good to know, thanks. I keep distilled water on hand for projects, so that's easy.

Question: Does dilution with distilled water not move the pH of the solution closer to 7.0? Perhaps the answer is: yes, but just not by very much (well within rounding error)...?

I do recall that pH is a log scale (I even recall that it's the negative log of Hydrogen cations) and the attendant orders of magnitude associated with the scale.

I *vaguely* recall (from some distant course and my work in reducing soil acidity) that there are buffer solutions that resist changes in pH (perhaps due to the pairing of acids and bases) but that the buffering capacity is greatly reduced as the buffer approaches pH = 7.0 (I'm definitely swimming in water over my head here, so I may have just misstated something.)

So, empirical data:

This morning I used the block test on the pool water and got a result of 7.4 (it seems the Boy Scouts did a fair job of aeration yesterday afternoon as it was previously 7.2 using the block test).

I calibrated my Hanna meter, tested the pool water, and got a result of 7.45 (pretty close to the block test).

After reading your post, I diluted a sample of pool water with 50% distilled water (total sample size of 44 ml). I got a result of 7.04 with the Hanna meter. I added 5 drops of reagent and got a visual color shade just north of 7.0 on the color blocks (definitely lighter than the 7.4 shade I got with 100% pool water).

So...it seems I may have made an error somewhere. One potential place is that I only performed the test once; another is my Hanna meter uses a glass bulb probe and I'm positive the electrolyte in it needs to be replaced, although it did successfully perform a two-point calibration. (At $70 for for probe electrolyte it's low on my list). This is all interesting science to me, thanks for bearing with my thinking aloud (in writing).

In additional good news, the Scouts likely helped lower my CYA as the auto-fill was running all night (although I'm sure it's not nearly enough)!

 

[needsajet]

No, the pH is buffered in the pool water, so little to no effect from adding distilled water. Perhaps try a new batch, and be sure it's not demineralized water (water used for cooling systems, filling the iron, etc.), and actual distilled water. Also sounds like your meter may be the handiest option.

Also note the comment below about testing right away. Note also that a lighter shade in the pH test just requires another drop of the phenol red. It's actual color difference that matters, with the range from sort of a burnt yellow, through red, and on to purple. Here's a thorough description from 2012, from a great past contributor far more qualified than me!

Dilution with distilled water (that has nearly 0 ppm TA) would work because it won't change the pH in a measurable way because of the pH buffering in the sample being diluted. The electronic pH meter would work, but can be expensive. The other methods reducing chlorine levels won't work because they can affect the pH themselves due to the pH of their buffered solutions and the dechlorination will usually lower the pH (remember that chlorine usage/consumption is an acidic process though it depends on the specific dechlorinating chemical that is used). The Taylor phenol red solution has a special combination of chlorine reducing agents that try to be as pH neutral as possible when converting chlorine to chloride.

However, in a pool with CYA, the oxidation of phenol red to chlorphenol red appears to be somewhat slow taking a minute or two. So if you measure the pH in a reasonable time, it is likely to be accurate. JamesW did some experiments that showed this. The fact is that shocking the pool to higher FC levels raises the pH. This is known and predictable. So when people see high pH when shocking, this isn't because the test is invalid but more likely to be a true reflection of the high pH. This is why I recommend lowering the pH first before shocking, most especially when shocking to high levels such as when the CYA is high or when going to yellow/mustard algae shock levels.

 

[mld213]

Good stuff, thanks. I went and read the full thread. I'll keep the speed of interference in mind, I usually do the phenol red test fairly quickly--about 10-15 seconds. That might not be fast enough at high shock levels, but seems to be working fine for me over the past few days. I'll likely use both the phenol red and the pH meter for a while to see how they correspond with each other.