What is Total Dissolved Solids?


LifeTime Supporter
Aug 19, 2009
Central New Jersey
Hi Everyone! I went to the pool store today to test my water because I had run out of my cya reagent their test results are as follows;

fac 3
tac 3
ph 8
ta 120
cya 50
tds 1650

What is TDS? Their recommendations are to partially drain and refill, I have lost some water already due to a small leak last week. I have been adding about 64oz of bleach everyday but also noticed that the water is starting to get cloudy and notice some algae. :grrrr:


TFP Expert
LifeTime Supporter
Feb 23, 2008
Denton, TX
TDS = Total Dissolved Solids

TDS is basically a test to show you how much is dissolved in the water. Anything, and I mean anything that is dissolved in your water will reflect on the TDS and this is also why TDS isn't of much use to us. After all, what good does it do for you to know something is in your water without knowing what it is? It is much better to know the individual components, rather than the sum of all of them.

You don't need to drain water, you need to shock your pool. Lower your pH to 7.2 using muriatic acid first. Your CYA is 50 and therefore, you need to raise your FC to 20 using bleach. Hold it at shock level until your water clears, you end up with less than 0.5 on your CC, and your overnight FC loss is 1 or less.


LifeTime Supporter
Nov 18, 2009
Sacramento, CA
TDS is irrelevant. Your FC is low for your CYA. At CYA = 50 you should always have it above 4, which means you targeting 6-8 when you add chlorine.

If you have algae you need to shock (instructions in my signature).

Also your pH is high. You need to add enough muriatic acid to lower it to 7.2 before you shock.


TFP Expert
LifeTime Supporter
Mar 29, 2007
Coastalish 'down easter'
Welcome to TFP!!

TDS is basically BS!

Pool stores who offer free testing often use it to get you to drain the pool and buy more chems from them :rant:

They'll often say the the water has lost it's 'elasticity' so newly added chems won't work properly.

However, the truth is that most of the TDS is salt and people purposely add ~ 3000 ppm of salt to their pools when they have a SWCG.

In short; TDS isn't something you need to worry about :-D


1,650 TDS is well below the 2,500-3,000 recommended upper levels as well. Sounds like somebody is trying to sell you something.........


LifeTime Supporter
Aug 19, 2009
Central New Jersey
Thanks everyone for your quick responses! I had never heard of it, I new better than to listen to him :goodjob: I was just curious of what it was. Now I'm starting to shock, I really don't know what happen to my water, I thought I had it under control by adding 64oz of bleach everyday.

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