calcium scale and acid wash (empty pool)

[alphadog]

I had a problem with calcium scale last year, but also had a problem with the glazing on my tile chipping so i decided to do an acid wash this year. I have a 20K gunite/plaster pool that is 4 years old.

I have a feeling the scaling was due to my high pH as the CH seemed to be fine - but no matter - I will get the water chemistry right when i fill it.

My question is this - I am acid washing with a 50/50 water/acid solution, and although the plaster looks very nice, I still feel the sharp - rough calcium. A pumice stone takes it off, but I don't really like the idea of rubbing the entire pool down.

I have already made 2 passes with acid wash. I am using a watering can - pouring it on, letting it sit for about 30 seconds and scrubbing and rinsing.... Should I up the concentration of acid? Any other thoughts?

I know I could do the no-drain method, but I don't have a heater bypass, and to put one in, I need to get some new union connectors for the filter and heater... just more work.

If this thread is in the wrong forum, feel free to move.

Thanks!

 

[JasonLion]

You are doing the right thing. However, if the scale is thicker than normal, it can take a couple of passes to get all of the scale off.

You can use more concentrated acid, but it is rather more difficult to work with and I don't really recommend it.

 

[alphadog]

Thanks, it sounds like I could make my mixture stronger... yeah, I don't really want to buy stronger acid - and if I recall, to get the stronger stuff you had to buy a carboy.

I guess I will try 75% acid to water, and I could always try a small spot at full strength.

Thanks for the feedback.

 

[prs]

I guess it all depends on the strength of the acid you start with. My local Home Depot has 14% and 31%. Diluting both of these to 50% will give you vastly different strengths!