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Greetings,

I have been reading the forum for about an hour looking for a solution to the problem in my mom's above ground, easy set pool. It's going crazy with algae and she wants to shock it but the chemistry is all out of norm. I think I have a plan, but would like to double check and get some advice. Here's the lowdown:

Pool Type

Intex easyset pool: 15'x4'

4440 gallons (though not quite full, maybe around 4000 gallons)

SWG- intex brand (I think, it's from Walmart)

Levels

CYA 150

TA >240

PH >8.4

FC 0

Hardness 1000

Salt 8.0- 6140ppm (I'm transcribing exactly how my mom sent the values, not sure what the two different values mean here, but it seems high nonetheless)

edit: tested with HTH 6 in 1 test kit strips.

Misc info

She has the SWG running from 8pm-11pm nightly like the book recommends.

We have very hard well water with high pH (our area has a lot of limestone)

My mom runs a water softening unit that also uses salt and the water that filled the pool went through this first.

edit: she has never added anything to it except for the initial salt as instructed by the SWG booklet.

Tentative Plan- please advise

1. Lower the CYA level by draining part of the water and refilling (but what if the well water is high in CYA? Maybe I should test it?) Also how much to drain? 1/2?

2. Add an acid to bring down the alkalinity. Which product is best for very alkaline/high pH well-water?

3. Add an acid to bring down the pH. Isn't this redundant? Use same product?

4. Brush the pool. Seems self-explanatory.

5. Shock the pool. Which product do you advise for use with SWG?

6. Vacuum the pool. Advice on a vacuum for an AGP would be appreciated, we don't have one.

Thanks in advance!

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CYA is not in well water or tap water so no need to test for that. Just replace at least half the water to lower the CYA level.

Yes, acid is used for lowering the pH and the TA, but for the TA you need to keep adding acid to have the pH be low (7.0 to 7.2) while aerating the water. Hopefully the water replacement will help out so you don't need to use as much acid. Also hopefully the CH will drop.

Test the well water for TA and CH. It may be high and that will be a challenge, though you can lower the TA as I described.

As for shocking to kill algae, use chlorinating liquid or bleach (unscented, plain). You don't want to increase CYA (from Trichlor or Dichlor) or CH (from Cal-Hypo).

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Thanks chem geek! So very helpful!!! I'm not sure what to use for the aeration but I will search this forum to find out. I will test the well water for TA and CH, my hunch is that they will both be high. Is high CH a problem long term? Are there ways to lower the CH too?

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You can usually manage by lowering the TA and keeping an eye on pH. If the CH is exceptionally high well over 1000 ppm, then one can use a metal sequestrant designed to reduce the risk of scaling, but normally that isn't necessary. The saturation index usually has to get pretty high, over +0.7, before scaling is seen -- the only exception I've seen to that is in hot spas where +0.3 can sometimes result in scaling, especially in the heater which is of course hotter so has a higher saturation index than the bulk water.

Unfortunately, there aren't easy ways to lower the CH. Water replacement with water lower in CH is the primary method. Reverse osmosis is another option, but may not be available in your area.

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Really strange, we tested the well water and it shows the same reading for the CYA, so we decided not to do a partial drain/refill since it seems pointless. I'm going to try to balance the pH and chlorinate/shock based on the high CYA level. It may be closer to 100, hard to tell with these strips and their subtle colors. I'd like to get a better test kit, will check out the Taylor. My mom really wants to get going on this though before the algae gets worse, so I'm going to do the best I can with what I know.

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The well water should not have any CYA in it. That seems very strange. What kind of test kit are you using? Is it test strips? A drop-based kit? Since you mentioned hardness and not calcium hardness, I suspect you are using test strips and those are useless. WAIT A SECOND -- I see in your post you ARE using test strips. They are useless, useless, useless. Before doing anything else, get yourself a proper test kit, the Taylor K-2006 (not the K-2005) which you pretty much have to get online since most pool stores don't carry it.

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I completely agree and if it were my pool, I would wait and get the kit first. However my mom had a bottle of the super shock in hand this afternoon (Cal-Hypo I think) and was intending to use it if I didn't get started. So far I've added 80 oz of muriatic acid with no effects apparent on the test strips after 2 hours. I added about 80 oz more and turned off the pump for the night. (I was confused about whether the pump should run to circulate the acid or be off to not aerate during the first step of lowering TA) Will recheck in the morning. Is there an acceptable kit that I can buy at Lowes or Walmart or OSH? I don't think my mom is going to put up with waiting for anything to come by mail, she is worried that the algae will get worse.

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The HTH 6-way Test Kit at Walmart is at least a drop-based kit that tests most of what you need, but the chlorine test is an OTO test do doesn't readily distinguish between FC and CC and it's only approximate in its accuracy, but at least it does not bleach out at high chlorine levels. You get TA and CYA tests, but the hardness test is for Total Hardness, not Calcium Hardness. Still, much better than test strips, especially for the CYA test.

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We purchased the HTH kit and it helped a lot thanks. We were able to finally get an accurate pH reading. Unfortunately the CYA test did not shed any light because it never turned cloudy, which is integral to performing the test. My guess is that the level is over 100, the highest value on the cylinder, and that's why it didn't work at all.

I saw an empty bottle of cell saver (for the SWG) in my mom's pool stuff and asked her about it. She forgot that she had added it. I looked to see if that's where the CYA could have come from, but it didn't show any ingredients on the bottle. I did see that it calls for using 16 oz in a 10,000 gallon pool, but my mom used all 32 oz. in a 4,400 gallon pool, so whatever is in it got added to the pool at 4x the correct amount.

The pH came down to 7.2 so we are aerating now, but the alkalinity is still showing high, over 400 ppm. Added more acid overnight but the levels are still the same.

The algae is getting bad, so we are going to move on to shocking it before it gets worse. I never knew fixing a pool would be so complicated, but this definitely drives the point home that an accurate test kit is going to save a lot of time and money. At least I am glad we got the pH to lower and knew which products to use to not make certain situations worse. Should be interesting to see how much chlorinating liquid it takes to bring it to a shock level, not knowing for sure what the CYA level is.

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If the CYA test never turned cloudy then your CYA level is 0. Period. end of story! Strips are notorious for giving bogus results on the CYA test but the melamine preicpitation test (disappearing black dot) is pretty bulletproof! If it never turned cloudy you have NO CYA in the water!

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And if your CYA level is truly zero, then you would have a heck of a time maintaining the FC level in your pool if it is exposed to sunlight since half the FC would be broken down every hour in direct noontime sun. You need to get some CYA into your pool, either adding pure CYA or in your case perhaps using Dichlor as your chlorine source for a while. Because you have an SWG, it sounds like no CYA was added to the pool and that was a big mistake. So either get some pure CYA into a sock to hang over a return to dissolve it relatively quickly or get some Dichlor and add it to the pool every day for a while (start with 10 ppm the first day to get things going) until the CYA builds up and then the SWG will be able to take over.

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