Please help me with my numbers.....

[lorngraves]

I have the TF test kit ordered. Scheduled for delivery tomorrow. PB left 2 different inds of test strips here for me. I get different readings with both. So today I took my water to the pool store. (The pool is about 3 weeks old)

FC 2.2
TC 2.2
pH 7.8
CH 320
TA 100
CYA 35

They told me to add more CYA since I am using SWC. I am hesitant to do that after all the reading here about having to up my chlorine with higher CYA levels. I have the Goldline Aqua Rite with the controls. There is an "ideal" range on the back of the manual that says stabilizer of 60-80 ppm. Do I really need to take it that high? Why or why not? Pool store told me to add 6 more pounds of stabilizer but I am holding off until I get some answers here.

Also, I just did add about 2 pounds of pH down as it is creeping up. (after getting back from the pool store) Will test that again later tonight.

They did say my CH was high. But that with backwashing it should come down eventually. Do I need to worry about that? Not sure how it got that high unless PB put too much in when they started the pool.

What do I need to do now? Thanks so much for any help!!

 

[JohnT]

You do need the higher CYA with a SWCG, and you won't normally have the problems associated with high CYA unless you have an equipment problem that allows algae to get started. The higher CYA keeps your cell from having to work so hard, which increases its life.

 

[JasonLion]

I would let the TA drift down towards the 70-80 range. It will tend to come down naturally, so don't worry about it till it goes below 70. That will slow the rate at which PH rises.

You will need to keep an eye on PH. Try to keep it between 7.2 and 7.8. Over time you will learn how much acid and how frequently you need to add it to stay in that range.

Your CH is fine. With a vinyl liner anything between 0 and 400 is fine. Don't spend any money or worry on it unless it goes over 400.

I recommend CYA of 60 or so. Your SWG will be able to work less hard and will last longer.

I would wait till you have numbers from your new test kit before doing anything except lowering the PH. Pool store numbers can be great and they can be way off. With the good test kit you have coming you should trust your own numbers over any other source.

 

[lorngraves]

So according to the chart with the CYA level of 60 my FC should be between 4.4-6.8. Will that not bleach out my liner over time with that high a level? What about bleaching bathing suits? The PB told me to keep the FC under 3 but I am sure he did not account for the CYA level. I surely don't want an algae outbreak.

Also, how do I know if I ever need to shock the water? Thanks for all the help!!

 

[JasonLion]

With CYA of 60 and a SWG you should be able to keep FC around 4 and not have any problems. SWGs allow lower FC levels than other sources of chlorine. The exact level that gives the best water quality varies a bit from pool to pool. If you want to experiment you might try FC of 3 and 5 and see if that looks any better than 4.

The effectivness of chlorine goes down with the CYA level. The higher the CYA level the more chlorine you need to have a given effect. At a CYA level of 60 bathing suits and the liner are safe up to around FC of 40.

You shock when any of the following things happen: the FC goes down to zero, there is obvious algae growing in the pool, CC is above 0.5, openning in the spring (if you close). If none of those things happen there is no need to shock.

 

[mas985]

I think the consensus of the forum is that SWGs can operate at less Chlorine ppm for a given CYA ppm than the BBB method. Chemgeek uses a min of 4.5% of CYA ppm rule and I usually run a little higher at about 5% of CYA ppm. So at 60 ppm, you probably can get away with a 3 ppm CL level. Last year I ran my SWG at about 2 ppm with a CYA of 60 ppm without any problems but I think that is pushing it a bit.

 

[lorngraves]

So I am sorta confused!! Once I add the CYA, I just added 4 pounds, do I need to turn my SWG back up to get a higher FC? It is now on 25% and I have 2.2 FC. Or will the CYA keep the chlorine from burning off in the sun and keep my SWG set at 25%? I guess I am having a hard time figuring how that will help my cell not have to work as hard when adding CYA to 60ppm, but then if I have to turn it up to make more FC what good is that? Sorry I am being so dunce! (I do have another 4 pounds of CYA I can add if needed)

 

[JasonLion]

First, it can take several days, up to a week, for CYA to fully disolve. So you might not see any change at first.

Adding CYA causes less FC to be lost to sunlight, so in the long run you should be able to turn down the SWG percentage and still have plenty of FC. Right at first it will take the SWG a little while to catch up to the somewhat higher FC level required at the higher CYA level, so you might need to turn it up for a couple of days. But then it should settle down and give the desired FC level at a lower percentage than you were using initially.

 

[lorngraves]

Thanks so much!! I *think* that is what I was thinking would happen but it was all so confusing. So should I wait about a week to test CYA again before adding the other 4 pounds. I am just afraid of getting it too high. I would like to keep it as low as I can but still work the SWG efficiently.

 

[JasonLion]

Yes, wait a full week from when you added CYA before testing it again.