what is: whitish powder film on the bottom of Baquacil pool?

White slimy stuff is sometimes called Pink Algae and can be a problem with biguanide pools that use products like Soft Swim and Baquacil.

This is actually a bacteria, not an algae.

I suggest this post:

Swimming Pool Algae With Baquacil Use

This normally doesn't happen with chlorine pools. It can, but not likely.

You'll need to clean the pool including the ladder, ladder treads, steps, in all the crevices of the skimmer.

Pretty much any place where there is poor water circulation.

Clean, clean, and more cleaning.

To get rid of this, you'll need to do a good double, or even triple, pool shock. Bring your chlorine up 20Xs.

You can find the information for that at this link:

Water Mold

Here's the pages and charts to chlorine and pool shock:

Swimming Pool Chlorine

Pool Shock

This sounds like alot of chlorine, and it is, but being this is a bacteria and not an algae.

It's a little tougher to get rid of so you'll need the extra chlorine.

You can also put a small dose of diluted chlorine in the skimmer to flush out the suction side.

Whatever kind of filter you have, you'll need to clean the it out or backwash. You want to reduce the amount of Baquacil in the system.

Don't put any Baquacil chemicals in the pool while the shock is going on.

I would encourage you to revisit the idea of using Baqucil and consider a chlorine pool.

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