Help with chemistry

[cwilli35]

Any help is appreciated...this is my first pool and it's a bit overwhelming!
To the best of my ability to assume a volume, I come up with ~27000 gallons
18' wide X 37' long -- 8-1/2' deep X 3-1/2' shallow = 6' average
Salt Water with new chlorinator
new Unicel filters - 420 in.

Here are my test results from Leslie's
6/1/2011
TAC - .5
pH - 8.0
TA - 200
CYA - 30
CH - 230
TDS - 5000
Phos - 200
Suggested adding 4 gallons Muriatic Acid - 1 qt every 4 hours to lower pH and TA

6/5/2011
FAC - 4
pH - 7.6
TA - 230
CYA - 0
CH - 240
Salt - 3700
Phos - 0
Suggested adding 2 more gallons Muriatic Acid - 1 pint every 4 hours to lower TA
Also 5 lbs conditioner in a sock placed in a skimmer basket to raise CYA

Can my CYA reduce from 30 to 0 in 5 days on its own with no rain or water added to pool?
Seems like I'm adding a lot of Muriatic Acid? is this normal? doesn't seem to be helping anything but pH.

Thanks in advance for your help, not only with my issue but with the entire site, it's a great tool!

Cheers!

 

[JasonLion]

Welcome to TFP!

What kind of pool is it: plaster, vinyl, fiberglass? Rapid PH increases are very common with fresh plaster. Expect to add acid every day for the first three or four weeks with fresh plaster.

CYA did not go down by 30, no way. Their testing is simply not accurate. You will have much more consistent results if you get your own top quality test kit. I recommend the TF100 from TFTestKits.net. The Taylor K-2006 is also good.

 

[cwilli35]

Pool is gunnite? plaster? but it's 2008 model.
i didn't close the pool over the winter (Edmond, Oklahoma) and we had quite a bit of snow and normal amounts of rain.
i kept a 3" chlorine tablet in the skimmers all winter and the pool ran 5 hours/night.
I will try another gallon of acid and see where it is.
I think I need to get pH and Alk. lined out then worry about the CYA & Chlorine.

 

[JasonLion]

Alright, then the rapid PH increase is coming from the high TA level. Keep lowering PH to 7.2 every time it gets to 7.8 and the TA will come down slowly.

You might also want to check the TA level of your fill water. It may be that TA is going up every time you add water to the pool.

 

[cwilli35]

Excellent point. I'm on well water and the water I fill with is straight out of the ground!
I bet you just solved my issue!

Thanks again, I appreciate it.