Test Results - Please Review

[Jacob99]

I'd rather you get 2 consecutive days of chlorine AND pH results, and let me see what they are, before you start pouring in acid. Low pH can damage pool liners. High pH is not good, either, but the effects are much slower.

Great. Thank you. I'll report back later on.

[Jacob99]

Unfortunately I didn't get to test yesterday. I was way too busy. I did add another pound of stabilizer yesterday though. I tested first thing this morning, and these are the results:

FC: 2.4
CC: 0.4
pH: 7.3 (didn't put any acid it - not sure why pH has been so jumpy)
TA: 60
CYA: 55!!

How the heck did my CYA get up to 55? The only thing I've put in is liquid chlorine, stabilizer, and a box of Borax (the one from 2 days ago). I put in a gallon of liquid stabilizer which was suppose to raise 30ppm for 10,000 gallons, I have almost 24,000 gallons so we'll call that less than 15ppm that I should've gained. Then I only added 3 of the 4 lbs of HTH powdered stabilizer. According to the label of the HTH stabilizer for a 20ppm increase in 20,000 gallons I should use 4lbs and I only used 3 of the 4 like I said. So, 20ppm plus the 15ppm of the liquid stabilizer = 35ppm which are the same numbers I got using the pool calculator, and since I only used 3 of the 4 lbs I should be under 35ppm. I'm confused where this extra 20+ppm came from. Is it possible that the water I had trucked in had some CYA in it already? I wish I had tested yesterday before adding that 3rd pound!

Another thing, I've been running my pump 24x7 the last 3-4 days since I've been putting in stabilizer, Borax, etc. It's been running on low, and I've noticed a decrease in pump pressure. On low, it was previously just under 10psi, but now it's under 5psi. What would cause that?

[PoolDoc]

Trucked in water didn't have CYA in it -- it's NEVER used in potable water treatment.

Stabilizer dissolves slowly, so what you added 4 days ago is only now fully dissolving. If you added granular stabilizer yesterday, you'll probably continue to see a rise in CYA levels over the next few days.

As a rule, a drop in filter pressure means a drop in flow, often because of a dirty strainer basket, or a clogged impeller. Is that a possibility on your pool?

[Jacob99]

How would it have climbed this high in the first place though? I definitely did not use enough stabilizer to get levels that high. I used 1 gallon of this:

http://www.intheswim.com/Pool-Chemic...r-Conditioner/

And 3 lbs of this:

http://www.walmart.com/ip/HTH-Stabil...Specifications

In a 23,900 gallon pool that should have given me around 30ppm or so....not 55.

[PoolDoc]

Partly, you're overestimating your gallons. Pool companies always quote volume at the 'running over the sides' level, not the actual level.

It's not really a problem, though, so I'm not inclined to put much effort into figuring out exactly how it happened.

[Jacob99]

LoL...I appreciate your honesty. So from a quick search here the rule of thumb is to keep FC at about 8% of the CYA?

[Watermom]

Take a look at the Best Guess Chlorine Chart below for the correlation between CYA and needed chlorine levels.

[PoolDoc]

So from a quick search here the rule of thumb is to keep FC at about 8% of the CYA?

That will work, most of the time. You can't kill established biofilms (slime, black algae, mustard algae) that way, however.