sanitizers

[Brazos Mike]

First post on the forum. Have been following the advice on the forum. Pool is about 2 months old (first pool for me). Here are my numbers:
FC-3.0
PH-7.8
TA-85
CYA-50
CH-100
I know ph is high and calcium is low. My question is: is cal- hypo safe for shocking in a salt pool? Local pool store said it should never be used with a swg. They were highly recommended and not a chain store. What do you recommend? Thanks.

 

[Richard320]

Welcome!

Yes, it's safe to use Cal-hypo. The question is, why do you want to "shock"? Is the pool sloudy or green? If so, a one-time mega-dose of chlorine probably won't fix it. If you maintain your pool chemistry properly with your own test kit, you might not ever need to deal with algae again. Have you done any reading in Pool School?

 

[jblizzle]

Welcome to TFP!!!

First, what do you mean by "shocking"? When try to avoid that term since it has too many meaning to too many people. If you mean a weekly arbitrary temporary boost in chlorine, we do not think it is needed if you maintain proper FC levels which are a function of your CYA level (See the FC/CYA Chart). If you mean dealing with algae, then we recommend following the SLAM Process.

You can use cal-hypo in your pool ... if you are aware of what it will do to the water by using PoolMath. Since you have a SWG and it is maintaining your FC level, it would be cheaper and easier to just add the calcium separately.

Note we also recommend a CYA up around 70-80ppm for SWG pools: See Water Balance for SWGs

 

[Brazos Mike]

Thanks for the replies. Actually the water is clear and haven't needed to slam since initial startup. The pool builder used, and left us, 10# of cal-hypo so I was curious why the PS warned us about it in a salt pool.

 

[Patrick_B]

With the CH level you list in your pool the Cal-Hypo is fine and I would use it. Pool Stores are often wrong and give misinformation.

SWG's run well with more CH in the water than you have, and perform perfectly.

A SWG has no idea where the CH came from, whether from the source water or Chlorinating product. Have no fear in using it, but once it is gone, see where your CH is before purchasing more.

 

[JohnT]

I would think this is an example of a pool store generalizing some advice that has a grain of truth without understanding why. When you shock a pool weekly using the pool store method, Cal-Hypo is problematic. Your CH rises and then you see a visible symptom with calcium flakes on the electrodes. The climbing pH in a SWCG pool can make a poorly maintained pool more prone to scaling when the CH gets high as well. Conclusion: Cal-Hypo is bad in a SWCG pool.

And they are right sometimes. Cal-hypo can cause problems in a pool, but so can chlorine, muriatic acid, CYA, baking soda, borax and washing soda.

Since most pool store workers don't understand the problems brought on by high CYA, they see trichlor and dichlor as better than cal-hypo because neither causes a visible side-effect that they associate with high CYA. They blame the algae and hazy water on TDS, phosphates or chlorine lock rather than the stabilized chlorine they are using for both routine chlorination and weekly shocking.

The problem isn't the stuff being added to the pool, but the fact that it is being added blindly without determining a need for it and without understanding everything it will do to the water.

That is the key difference between TFPC and the pool store method. TFPC relies on knowing your water and knowing the effects of adding chemicals, while pool stores (in general) rely on rules of thumb, generalizations and downright misunderstanding of water chemistry.