Test Results - Please Review

[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.

[Jacob99]

I tested my CYA again today. I think yesterday's results weren't accurate. After reading some more on this site, I guess the CYA should be tested on water at room temperature, but I tested with water immediately out of the pool which was only around 55 degrees. I got a new water sample first thing this morning and just tested it. I also tested outside for lighting purposes. Results today are between 35-40 which is right around my original target.

However, today my CC crept up from .4 to .8. My water is still pretty darn clear, but maybe I have the start of an algae growth? I haven't been able to brush my walls or vacuum my pool bottom due to the water temps. Pool was installed too early in the season!

FC: 2.6
CC: 0.8
pH: 7.2
TA: 60
CYA: 40ish