problem after adding calcium

[poolnewbie4]

I added calcium to my pool recently and I can feel some hard calcium crystals on the bottom of my pool now when I brush the floor which is difficult to remove. I brushed several times afterwards so I’m not sure why this happened since it never happened before. I need to add some more calcium to my pool since my level is only at 130 so I was thinking about dissolving it into a bucket of water this time to prevent this from happening again. It says on the bucket of Clorox Calcium Hardness Increaser that an adverse chemical reaction can occur if it is predissolved first. What adverse chemical reaction are they referring to and could this cause any problems to my pool?

 

[mknauss]

Adding calcium chloride to water is an exothermic reaction. It heats up fast and can burn.

It is best to add to the pool in small amounts to the deep end.

 

[poolnewbie4]

If it gets hot when added to water, does it get hot enough to burn or damage the surface of the fiberglass pool if some of it settles to the bottom and hardens again like it did last time? I only added 5 lbs of it to the deep end last time and it seemed to quickly settle to the bottom and clump up before I was able to brush it all up.

 

[mknauss]

The volume of the pool is exponentially larger than the volume of a bucket. So heat dissipates immediately.

Be sure to broadcast it across the deep end. Do not dump in one spot. And then brush.

If your CH is low, it should dissolve rapidly if pure calcium chloride.

 

[poolnewbie4]

Thanks for the advice. I’m adding it in smaller batches now and it is dissolving a lot better. How long do I need to run the pump after adding calcium and how soon can I add chlorine after adding it? I’ve noticed that my PH went up from 7.4 to 7.8. after adding 5 lbs of calcium yesterday but I wasn’t sure if the calcium caused this or if it was caused by adding chlorine too soon after adding the calcium. Before adding any more calcium tomorrow, should I lower the PH if it is still at 7.8?

 

[mknauss]

You can add the chlorine at the same time as the calcium. They do not react.

You should not test pH right after adding chlorine. It will always read high. Test pH prior to adding your chlorine for the day.

I do not know if you need to act on a pH of 7.8 as I do not know your other chemistry parameters.

 

[poolnewbie4]

The PH tested at 7.8 before I added the chlorine. All of other chemicals were within range except calcium is still low (FC=3, CC=0, CYA=30, TA=110, CH 180.). Is the calcium causing the PH to rise and do I need to lower it before adding more? It’s too cold to swim right now and I hate handling muriatic acid so I wanted to check to see if lowering PH was necessary before adding any more calcium to my pool.

 

[mknauss]

Calcium has no effect on pH.

Your pH rises because your TA is high.

 

[Phlow]

I have been mixing 5lbs calcium in a 5gal bucket submerged in the pool and using a stick to swirl it around. The Clorox bottle says don't do it, but honestly, if you keep it in the pool the heat dissipates with no problem. Just sink the bucket lip to pull in some water near the top, swirl it around with the stick to help dissolve. Poor some out, pull more water in, swirl, poor out, repeat. Haven't had any problems with undissolved calcium yet.

 

[mknauss]

I have been mixing 5lbs calcium in a 5gal bucket submerged in the pool and using a stick to swirl it around. The Clorox bottle says don't do it, but honestly, if you keep it in the pool the heat dissipates with no problem. Just sink the bucket lip to pull in some water near the top, swirl it around with the stick to help dissolve. Poor some out, pull more water in, swirl, poor out, repeat. Haven't had any problems with undissolved calcium yet.

Good for you. But not recommended.

Pool School -- Calcium products should be spread across the surface of the deep end of the pool.