Replace the water or not?

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R

Red

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Sep 11, 2010
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Orange County, CA
We replumbed and replastered with PebbleTec back in 2010. In 2017 we drained the pool and did an acid wash, as that's what I thought you were supposed to do (we also needed to drain it to add some mini lights for safety, after we realized that the dark PebbleTec surface didn't reflect light the way the previous white plaster did).

Here we are 8 years later and I thought I should change the water and get an acid wash again. Replacing the water would also lower the CH, which has been in the 550-625 range the past 6 months. Then I thought...go see what TFP people say about this before spending your money. What I've read at TFP and other sites has pretty much convinced me not to do an acid wash. I'm not dealing with stains. Yes, I have some calcium on the tile and could get someone to do glass bead blasting if it bothers me enough (which I'm not sure it does). But acid wash isn't going to help the tile, anyway.

Then it comes to replacing the water. After reading some posts here, I'm not sure that's necessary, either. Some people have suggested not doing that until CH gets to 1000 or more, but in the past, I think others have said when it's getting around 600, it's worth at leat a partial drain to lower the CH.

The last swim season (2024), I seemed to have more algae problems than usual, and that's also been true over the winter, when the water was down in the 60F/15.5C range. I did raise my CYA about 6 months ago, as I'd previously had issues with it being too low and dropping, but after I raised it, it's held pretty constant for the last 6 months at around 90. I'm not sure how CYA and algae relate. I thought raising the CYA might help things, but I'm not sure it did.

I've read some things that said an acid wash could help with algae problems, but I'm not sure that's the case. Some companies who do glass bead blasting also advocate doing that to the whole PebbleTech surface instead of an acid wash. Is there any value in that?

My thought is to only do a partial drain. This would lower CH and CYA. After filling it, I can SLAM and get the water back in order - and then clean the filter (the pressure's getting high and will be worse after a SLAM). Does this seem like a good plan?

My numbers are below. I let it get a little bit out of whack, as I thought I was going to completely drain the pool in the next week or two, anyway. FC is high. My SWG keeps making more chlorine and the algae keeps growing. I just dialed it back a bit.

FC 10.5
CC 0.5
pH 7.4
TA 60
CH 550
CYA 90
 
Red said:
We replumbed and replastered with PebbleTec back in 2010. In 2017 we drained the pool and did an acid wash, as that's what I thought you were supposed to do (we also needed to drain it to add some mini lights for safety, after we realized that the dark PebbleTec surface didn't reflect light the way the previous white plaster did).

Here we are 8 years later and I thought I should change the water and get an acid wash again. Replacing the water would also lower the CH, which has been in the 550-625 range the past 6 months. Then I thought...go see what TFP people say about this before spending your money. What I've read at TFP and other sites has pretty much convinced me not to do an acid wash. I'm not dealing with stains. Yes, I have some calcium on the tile and could get someone to do glass bead blasting if it bothers me enough (which I'm not sure it does). But acid wash isn't going to help the tile, anyway.

Then it comes to replacing the water. After reading some posts here, I'm not sure that's necessary, either. Some people have suggested not doing that until CH gets to 1000 or more, but in the past, I think others have said when it's getting around 600, it's worth at leat a partial drain to lower the CH.

The last swim season (2024), I seemed to have more algae problems than usual, and that's also been true over the winter, when the water was down in the 60F/15.5C range. I did raise my CYA about 6 months ago, as I'd previously had issues with it being too low and dropping, but after I raised it, it's held pretty constant for the last 6 months at around 90. I'm not sure how CYA and algae relate. I thought raising the CYA might help things, but I'm not sure it did.

I've read some things that said an acid wash could help with algae problems, but I'm not sure that's the case. Some companies who do glass bead blasting also advocate doing that to the whole PebbleTech surface instead of an acid wash. Is there any value in that?

My thought is to only do a partial drain. This would lower CH and CYA. After filling it, I can SLAM and get the water back in order - and then clean the filter (the pressure's getting high and will be worse after a SLAM). Does this seem like a good plan?

My numbers are below. I let it get a little bit out of whack, as I thought I was going to completely drain the pool in the next week or two, anyway. FC is high. My SWG keeps making more chlorine and the algae keeps growing. I just dialed it back a bit.

FC 10.5
CC 0.5
pH 7.4
TA 60
CH 550
CYA 90
Click to expand...
Your FC is barely high but if you have algae it’s not high enough. How sure are you that the CYA isn’t more than 90ppm? Increasing the CYA means you need to increase the FC to stay sanitary.

Your CH isn’t high and I wouldn’t trust the pH reading when the FC is over 10ppm.

If you have algae, then it’s time to SLAM. Acid washing isn’t needed, but replacing water to lower the CYA to a more manageable level for SLAM might be worth while.
 
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Doing a partial drain would help lower CYA and CH however your CH is not high by TFP standards.
Replacing 20% of your water will also lower the CYA and Ch by 20%. So decide if you want to reduce by 20%, 30%, etc.
Do not do an acid wash - causes more damage than good over the long term.

Are you using the PoolMath app? It is a great addition to pool management. You can input your test results and achieve a CSI reading that shows overall “balance” of your pool.
 
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Endro32 said:
Also check out the Pool School article on the CYA test, if you haven't already. It's pretty challenging to get good, consistent results, especially on the higher end, and reading it incorrectly could cause you to set your target FC too low.
Click to expand...
I have the Pentair CYA test...it's a tube with a scale I can move up and down until the dot "just disappears" to measure CYA (like this: https://www.amazon.com/Pentair-R151226-Cyanuric-Acid-Test/dp/B004VU8WVE/). The one that came with the Taylor kit frustrated me, so I got that other one instead. Is the Taylor test better and I just need to learn to deal with it? Or is the Pentair kit fine, too?
 
Red said:
I have the Pentair CYA test...it's a tube with a scale I can move up and down until the dot "just disappears" to measure CYA (like this: https://www.amazon.com/Pentair-R151226-Cyanuric-Acid-Test/dp/B004VU8WVE/). The one that came with the Taylor kit frustrated me, so I got that other one instead. Is the Taylor test better and I just need to learn to deal with it? Or is the Pentair kit fine, too?
Click to expand...
The Taylor version is easiest if you just fill the tube up to each line and check if the dot is visible or not. If it isn’t, then fill to the next line and repeat.
 
Red,

Both the CYA test that came with the Taylor kit, and the Pentair sliding dot, work just fine.. Both tests requires you to interpret the results... They are both somewhat subjective.

In my mind, the key is to do the test the same way every time..

Thanks,

Jim R.
 
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+1 to only filling to the 10s. We round up so 31 to 39 is a 40 anyway, and there's no need to split hairs.
 
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