TDS of 3700 after changing water

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pflood4150

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Mar 3, 2016
32
Gold Canyon, AZ
I just changed my pool water 2 weeks ago because the CA had reached 1000ppm. I just took a sample of the water into Leslies for testing and they reported that the CA was 200ppm but the TDS reading was 3700 whereas it should have been closer to 350! The only chemicals I added after the complete change was 2.5# CYA, along with 2 gall
of liquid Chlor and 1 gall muriatic acid. and apart from the cya the acid and CL were added in stages over that 2 week period. The suggested remedy for this was to change the water again (to what point if I use the same water supply co) or to add some chemical for around $50. Don't remember what.

Could this be for real?
 
Welcome to TFP!

Well, the most important piece of advice we can give here is ignore almost everything Leslies ever tells you about water. In this case specifically, TDS is an old and fairly meaningless measure of water quality. It is not the total that matters, it is what specifically is dissolved that matters. Most of that 3700 (if that is a real number) is probably just salts, which are relatively harmless.

So the first thing I am going to tell you is that you might not have to replace any water and almost certainly don't have to replace all of it. If you would like us to help you get better at managing your own pool then there are a few things you will need to do to get started:

Step 1: You need accurate test results. For various reasons we really can't trust any pool store testing as they are rarely a reliable source of accurate testing. You need your own kit, but not just any one. We strongly recommend the TF-100 or K-2006 as they have all the necessary tests, including the FAS-DPD chlorine test that is missing from almost all other kits. I have a link in my signature to one store that carries them, and no I do not get a kickback if you buy there.

Step 2: We need some information on your pool. Please update your signature with the information outlined here: What we need to know to answer your questions

Step 3: While waiting for your kit to arrive you should start reading up to get an idea how we operate and what you will need to do to care for your pool going forward so you can avoid getting questionable pool store advice in the future. Here are a couple links that will give you a good foundation on which you can build your pool knowledge:
Pool School - ABCs of Pool Water Chemistry
Pool School - Recommended Pool Chemicals
Pool School - Recommended Levels

I hope you find this helpful and please ask any questions, we are here to help!
 
Welcome! :wave:

TDS is useless. I don't know what mine is or has ever been, but I've never had green water and the scaling I inherited is slowly disappearing.

So take a sample of the tap water you used to fill the pool to Leslies and ask what the TDS is in that. Odds are, it will also be super high. Then you ask how replacing the water with that will change things for the better. Then you leave and only go back when you need obscure bits of hardware or pool toys that are on sale.

If you don't have your own test kit, you'll be at the mercy of the pool store forever.
 
What they all said, using TDS to manage water is straight out of the 1960's (ok maybe the 1970's), back when there were not easily available tests for each of the primary things (salts, CYA, Calcium) that make up TDS
 
I would suspect that that number is unlikely. Have it retested somewhere else. You could use the k-1766 to measure chloride specifically.

If you can get a new test of the tds, the calcium hardness and the salinity based on a chloride titration test, that would help better understand what you're dealing with.

What was the source of the water? If you bought the water, the seller should be able to provide a water quality report.
 
I do use a Taylor test kit K-2006 but this does not test for dissolved solids. The test meters for TDS are very expensive, and so far as I know they do not test for specific dissolved solids. It seems that unless I know what they are, how can an unknown be treated? Like you, I do not trust Leslies, the only reason I took a sample of my new water to them was for a CH test as I had ordered a replacement reagent for my kit which had not arrived. I had stopped using the store nearest to me after I was lied to by the manager who claimed that the unscented 8.2% bleach I was using was totally different to Chlorine and not just a lower strength! Seems all their employees are just as bad! They also claimed the phosphates were high and I should buy their phos free - only $50.

BTW Could not find link to edit profile,
Gold Canyon Arizona,12000 gall pebbletek pool built 2009, Sand filter.
 
TDS is not important. You do not need to test for it, you do not need to do anything about it. You do need to get your reagents for the calcium test, since that in range is very important with your pebbletek pool, but there is no reason to worry one bit about TDS.
 

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When one is expecting a tds of 350 on a fresh fill and it comes in at 3700, it might indicate that there might be a quality issue as the water is not what was expected.

TDS affects ths CSI, which is relevant to the plaster.

The salt level will affect a SWG.

If the source water is at 3700 ppm, then it's only going to get higher with evaporation and refill. If there's a SWG, the salt level could quickly get too high for the unit to operate.

In any case, it wouldn't hurt to better understand the source water to manage the pool water quality going forward.
 
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