Help me with My Numbers?

[mkfmedic]

Hello,

Tested my water today and have the following results:

TC - 2
CC - 0
FC - 2
pH - 7.8
Alk - 60
Cal - 400
Salt - 3200
Cya - 90

My SWCG has been OFF since February 14th, with only the DelOzone running with the pump about six hours a day. The weather had been beautiful recently, and it is currently about 78F here in Huntington Beach. The pool is covered by a safety net and has had no swimming load with the exception of using the spa a couple of times in the last month. The only thing added to the pool for quite some time is acid, which I do every 2 to 3 weeks (1/3 gallon).

My pool is 15 x 21, 3.5' - 5.5' in depth with a raised, attatched 7' spa, and a tanning shelf. My equipment is all Jandy and includeds a Heater, SWCG, DelOzone II generator, DE filter, 2hp pump for the filter and circulation and a 1.5 hp pump for the water features (8' sheer descents). The completed pool is approximately 8 months old.

This is the first time in quite a while I have seen my chlorine at 2. As the weather warms up, I'm sure I will have to turn the SWCG back on, probably to 5%. During peak summer swim season, the highest I have had to set it is 15%. There seems to be no algae, the water is clear, and the rock work seems to have no build-up of any sort. However, when do I need to be concerned about the Calcium numbers. 400 seems high, and if so, how do I lower it without effecting all the other numbers? Is that possible?

As always, any input, information or feedback would be greatly appreciated!

Thanks and happy swimming!

Mike

[chem geek]

Mike,

I wouldn't worry about your calcium. It is definitely not too high given your lower TA level. I assume you may be keeping your TA low to slow down the pH rise normally associated with an SWG. Your higher CH is good to have when the TA is low.

Your CYA is at 90 which seems high. Even the SWG manufacturers say "70-80 with 80 best" though we aren't really clear why they say that (we have some ideas, but no definitive answers). So if you lower your CYA a little by dilution, then your CH will lower a little as well (and your TA will also, so you'll need to add more of that).

If you were planning on lowering your pH from the current 7.8, then the combination of low TA with lower pH (say, 7.5) might just start to be something to take a look at -- normally you would increase the TA at that point, probably to 80, but there is nothing wrong with running your pool closer to a pH of 7.8 since that pH with a TA of 60 should have less pH rise over time.

Richard

[mkfmedic]

Thanks Richard,

I have been attmpeting to keep the Alk low to slow pH rise. Advice I learned here on the site. I have been watching my Cal rise over the last few months and have begun to worry when too much is too much. I appreciate your advice and input.

The Cya is another story. I have not added any since I originally started the pool, so there is a possibility that that number may be the result of user error. From what I understand, Cya cannot be removed without dilution, but it should not rise without the addition of Cya?

I will recheck my numbers and look at the Cya numbers again and if it still remains high, I reduce it through dilution and then raise the TA appropriately.

Thanks again,

Mike