numbers getting better, I think

[smuggs]

So, I now have a test kit (Taylor DPD Complete). I shocked on Friday night with 8 gallons of 6% bleach. FC and TC came in at about 15. As of tonight, I'm getting FC and TC of about 6 (we had a beautiful cloud-free day today). Here's the rest of my numbers based on my own testing:

FC = 6
TC = 6 (CC = 0)
TA = 80 (little low I believe)
pH = 7.4
CH = 90
CYA = 30

So, my CYA is now getting into range, but my CH seems to be going down from last week. The pool is 2.5 weeks new. Others have told me not to get too concerned about the CH just yet, but seeing it going down doesn't make too much sense to me. I have added about 2-3 inches of water over the last 1.5 weeks due to a lot of splash out by the kids in the spa with the blower on while NOT in spa mode.

Key Pool Stats:

28,000 gunite w/ white plaster
60 Sq Ft DE Filter
Chlorinator with Trichlor tabs

Any thoughts for the reduced CH? Should I plan on adding calium chloride at this point?

 

[JasonLion]

As the plaster cures it will raise the PH, TA, and CH. The majority of this happens in the first three or four weeks. I wouldn't worry about either TA or CH just yet, but it does look like you will need to raise the CH level fairly soon. Check TA and CH again in a week and see where you are then.

The CH test is +-10, so an apparent reduction of up to 20 between two tests might just be the normal error range of the test.

 

[smuggs]

As a follow up, I also noticed some black marks on the bottom in the deep end. They look like small scape marks and are not round (as I suspect would be the case if it is black algae...though since I'm new to this, I don't know. If I try the trichlor tablet approach to removing a stain, how long should I leave the tablet on the mark before to see if it is working to remove it? I've already tried brushing the marks.)

Thanks!

 

[JasonLion]

When trying trichlor to remove stains, rub gently for several seconds, don't leave the tablet sitting there. If the trichlor is working you will see some change in appearance very quickly.