CH = 400 too high for a new gunite/pebble pool?

[chem geek]

Thanks Pat. I forgot about the curing process which produces calcium hydroxide, Ca(OH)2, which of course adds calcium to the water and is highly alkaline. Doh! Thanks again.

Richard

[joelq]

Hi all - thanks so much for all the help. I should have paid much more attention in Chemistry class!

Here are my numbers as of 15 minutes ago:

FC: 3
CC: 2 (had 7 teenagers in the pool last night so will need to add some bleach! )
TC: 5
pH: 8 (as is usual for my morning water)
Alk: 90
CH: 425 (although using a different method from yesterday - I followed the high-calcium procedure for the Taylor K-2005)
CYA: 55
Salt: 2900 (according to the Aqualogic PS-8), 3200 (according to Taylor salt test kit)

A couple other details on how I've been testing: when I test the pH first thing in the morning, it is always at 8 or slightly off-scale. I put in 40 oz muriatic, and I re-test around 4 PM and consistently get a pH of 7.4. Does this make sense? As for the water volume of 12000, I'm pretty comfortable with it as I read the water meter before and after the pool was filled, and that's how I derived the figure of 12000. I'd say give/take around 1000 gallons to take into consideration our normal household water use.

I've also done some tests with Lamotte test strips, and the numbers are consistent with my drop test kit. I'll take some water over to Leslie's as well.

Assuming my CH readings are correct, however, should I do something to lower it now?

Thanks everybody!

[joelq]

Hi all - just went to Leslie's and got the following results:

FC: 5
TC: Not tested (didn't notice until they dumped all my water out)
pH: 7.4
TA: 100
CH: 380 (using the 10ppm/drop method)
CYA: 60
Salt: 3300

I also ran a test with the same batch of water I took to Leslie's and got the following results:

FC: 3
CC: 2
TC: 5
pH: 7.2
TA: 70
CH: 375 (using the 25ppm/drop method)
CYA: 60
Salt: Didn't test

Notice the drop in pH after I put in 40 oz of muriatic at 1.5 hours ago.

Maybe I need to tighten up my testing? Specially the CH testing?

[PatL34]

When you backwash, see if you can use softened water to refill. It is about the only way to bring it down, other than using chemicals used for that purpose. CarlD or Waterbear may help you here.

Pat