My First Complete Water Test

[HowardL]

Have had a pool for 10yrs, but recently moved to another home with a SWG pool with a cartridge filter. Filter was filthy, SWG cell was scaled up. Last week I had 0 FC with a shutdown SWG. I cleaned filter and cell and things have been humming along well since Friday.

Today I did my first complete water test and here's what I got...
Salt 3800
FC 7.0 (running cell @ 100% for a couple days; will turn down tonight or tomorrow)
CC 0
pH 7.8
CYA <30 Partially (mostly) obscured
TA 120
CH 220

Other than lowering the pH a bit, what should I do now?

Any and all suggestions or warnings appreciated by this SWG newbie. Thanks.

Howard

 

[jblizzle]

Check out this table:
pool-school/recommended_levels

For a SWG, a CYA level of 70-80 is recommended. SWG allow the FC to be maintained at a lower level as it is continually added to the pool. To protect the lower level, the CYA needs to be a bit higher.

Also check out http://www.poolcalculator.com where you can put in your current levels and target levels and check the CSI. If this get too negative you may harm your plaster. If it gets too positive you may start to scale (like your cell did).

Given your levels and assuming 70 degrees ... your CSI is -0.03 ... looking pretty good. With SWG I think the goal is a little more negative to reduce the scaling on the cell. If you raise the CYA to 70 and lower your pH a little bit seems like you water would be close to spot on.

ETA: It is not uncommon to use bleach to bump the FC a bit before/after any high usage to make sure the FC levels stays in the green. Typically it is not effective to try to use the "super chlorinate" function of the SWG as it does not add FC fast enough and just wears out the cell faster.

ETA2: Just wanted to point out that with your TA a little high, that will tend to pull the pH up as well. You could follow the Pool School article about lowering the TA and hopefully stabilizing your pH and then bump up the CH a bit to keep a good CSI. Then again ... if everything seems pretty stable now ... why mess with a good thing.

 

[linen]

jbliz has covered everything well :!: How does the water look?

 

[HowardL]

Water is clear as a bell. Didn't look quite so good when the SWG cell was not making chlorine, but I caught it before everything got out of hand.

Just to reconfirm, I should increase CYA, lower TA, lower pH and dial back my SWG. Doesn't sound like any showstopper to me. Great news. Thanks.

Howard

 

[ping]

Turn your SWG back to 50% and monitor your FC everyday for a week or two. By then you should be able to dial it in for the FC/CYA level you want.

I would increase the CYA and shoot for 60 ppm. Eventually you will want your CYA to be in the 70-80 range.

Since you have a SWG and your CH is 220 ppm, keeping your pH in the 7.5/7.8 range is fine. Your TA will likely come down slowly when you start to control your pH with acid. Your TA is not causing any problems so I would leave it alone for now. If after some time you feel that you need to add acid too often then you might consider lowering the TA to help prevent the pH rising so fast.

Don't worry about the TA for now that will trend to lower itself when you start to add acid to control the pH.