Testing a SWG Pool

[waterbear]

I just installed an Intex 6453gal above ground pool with an SWG. It came with all the lousy test strips. I know I need a good drop test kit but am curious what levels I need to be looking for, and are all test kits created for salt and chlorine pools? I owed an inground pool several years ago so I'm some what knowledgeable as to what I'm doing. *I used poolforum.com as my bible back then!* I'm heading up to Leslie's soon and what to be well informed as not to be "pool stored!" Thanks guys!

http://www.poolforum.com/pf2/showthread.php?t=9664
Scroll to the end and read my post.

[dustybecca]

Ok got my test kit, muriatic acid, and some stabilizer. From what my manuals state it takes my pool 4 hours to cycle the water. I've been adding 3 cups at a time of muriatic acid to lower the pH to 7.2, in 2 days the TA has only come down from 250 to 200. If I let the pH rise back up so does the TA. What am I doing wrong? Also I haven't added any CYA yet, I'm at 30 there and even though I have the SWG I can't keep any chlorine in the pool. I've been adding 3 cups of bleach a day to bring the FC to 1.5 but by the end of the day *with no swimmers* it's back to 0. I'm running my pump and SWG at the minimum 8 hours a day. Here are all of my readings
FC 0
pH 7.2
TA 200
TH 100
CYA 30

What am I doing wrong?

[waterbear]

If you are not adding anything to raise the pH up but letting it occur naturally then the TA is not rising any appreciable amount. The reason the pH is rising is that you are gassing off C02.
Let me start at the beginning:

1) your pool is carbonated like a bottle of soda. The carbonation comes from the bicarbonates in the water. We call these bicarbonates TA and we do want some because they act as a pH buffer.
However if there is too high a concentration the tendency is for the pH to settle around 8.0 which is higher than we want.

2) by adding acid we convert some of the bicarbonates to carbon dioxide (pour vinegar on baking soda to see this happen!). We have just lowered the TA since TA is only the bicarbonate (and carbonate) part of the buffer.The other part is the carbon dioxide but this does not count as TA because carbon dioxide in water is an acid and not an alkali.(At normal pool pH most of the TA is in bicarbonate form but as pH goes higher some does convert to carbonate form.)

3) Carbon Dioxide in water is carbonic acid. This is the fizz in your soda!
Shake up the soda and it goes flat because we have outgassed the carbon dioxide. The pH has also gone up because we have decreased the amount of carbonic ACID (CO2 dissolved in water) that is present. Operative word here is acid.
So how do you shake up a pool? Aerate the water any way you can. Carbon dioxide will gas off without agitation but it takes a very long time. Aeration is just a way to speed it up. (If you leave a bottle of soda uncapped it will go flat in time but if you shake it you will cause it to go flat much quicker.

SO...When you add the acid and drop the pH you have lowered the TA. Period.
When you wait for the pH to rise naturally or put your finger on top of the pool and shake it up!...er, I mean aerate the water in some way to speed the process up you raise the pH with no impact on TA.

Hope this is understandable.

Here are all of my readings
FC 0
pH 7.2
TA 200
TH 100
CYA 30

What am I doing wrong?

What is your salt level? If the salt is where it is supposed to be I would bump up the CYA to 50 and see if it helps. If not I suspect that your unit is not functioning properly.

[dustybecca]

Ok so I just need to stay on top of the pH and keep it low, and continue to aerate to "bubble off" the TA. I'm working on trying to find a salt test kit. I'll post those shortly.

[waterbear]

Ok so I just need to stay on top of the pH and keep it low, and continue to aerate to "bubble off" the TA. I'm working on trying to find a salt test kit. I'll post those shortly.

The AquaChek salt test strips are generally easy to find and are not that bad. I tend to use them a lot (and I also have a salt meter and a titration test for salt.)
I have found them to be within acceptable range of the other testing methods.
However, the are sensitive to humidity so keep them dry. I store mine in an air conditioned house.

[dustybecca]

Salt is at 2930 ppm. I've been running the SWG almost 16 hours a day and it still won't keep FC up.

[PoolDoc]

Apparently, SWCG's are sized with the assumption that you'll have 60+ ppm of CYA in your pool.

Get some dichlor (sodium dichloroisocyanurate) -- almost all the quick dissolve shock at places like Walmart is this stuff -- and use IT to get your chlorine up, and keep it up UNTIL your CYA is more than 60.

Then see if your SWCG will maintain.

PoolDoc.