When to test with SWCG?

[jlosurdo]

I just did my weekly testing, and these are the results:

FC - 10.0
CC - .5
CYA - 40
pH - 7.87
TA - 100
CH - 225
SALT - 3000

I pulled the sample about 1 hour after my morning filter run (4.5 hours) stopped. Should I be concerned about the 10.0 FC? Meaning, should I reduce the chlorination % (which is currently 70% for 8.5 hours a day)? Or is that normal since I tested right after it turned off? If I can get away with lowering it and adding life to the cell (which is brand new), I'd be happy!

I've also noticed that my pH creeps up pretty significantly each day (.1 to .15). I've been adding the Pool Math prescribed acid amount, but not sure if it is normal for it creep so much.

As always, thanks.

 

[Texas Splash]

Your FC is a little high, but not hurting anything at all. You can either reduce the SWG output or pump run time slightly to allow it to fall a little. Normally we would encourage you to lower the TA a little to help reduce pH rising so fast, but your CH is on the low end, so a higher pH and TA help to compensate. As long as the CH is at 225, I would let the TA stay in the 80-100 range and the pH around 7.8. Once your CH increases, possibly from seasonal hard water top-offs, then you can get more aggressive with lowering the TA down to about 60 which should help slow the rise of pH.

 

[jlosurdo]

Your FC is a little high, but not hurting anything at all. You can either reduce the SWG output or pump run time slightly to allow it to fall a little. Normally we would encourage you to lower the TA a little to help reduce pH rising so fast, but your CH is on the low end, so a higher pH and TA help to compensate. As long as the CH is at 225, I would let the TA stay in the 80-100 range and the pH around 7.8. Once your CH increases, possibly from seasonal hard water top-offs, then you can get more aggressive with lowering the TA down to about 60 which should help slow the rise of pH.

Thank you for such a helpful answer. I see that you are also in Texas. It's going to be 100 here in Austin today; still great pool weather.

 

[Jimrahbe]

J,

You should try to keep your FC at or above your target FC in the saltwater section of this chart... FC/CYA Levels

When you shut off the pump, obviously the SWCG quits making chlorine, and the pool keeps using chlorine. You really want to test just before the pump and SWCG start up again.

The whole idea is that you want your FC to be at your target when the SWCG has been off for the longest time it will normally be off.

As an example... It does you no good to have an FC of 4 right after your cell shuts off, if it is going to drop to zero before the SWCG comes back on.

Thanks,

Jim R.

 

[Newdude]

As an example... It does you no good to have an FC of 4 right after your cell shuts off, if it is going to drop to zero before the SWCG comes back on.

^^^^^^^^^^^^^^^ this right here.

The same with liquid chlorine folks. You want your lowest point to be free and clear above minimum, preferably never going below target range. Go however high you need to achieve that. If you choose to add that much plus a little for wiggle room, then that's even better.

Folks are obsessed with decreasing their chlorine. It's mostly industry's fault for brainwashing the masses about 1-4 ppm with no regard to CYA levels, but everybody who skimps on FC finds themselves in the Algae treatment section here. It might take a month or even three, but they'll be posting a SLAM thread.