We do have the “usual” type of pool. You are absolutely right about the cost, maybe a little low we, live in AZ
I could just not imagine cutting a whole in the bottom of the pool to drain it,
I must have misunderstood what you said.
Now taking care of a spot of black algae, any ideas ?
I have a pool business ...
Since you’re in AZ the hole in the bottom would seem odd ,, where I’m at in Florida it’s a normal part of the process when you drain a pool to refinish it.. The hole isn’t to drain the pool ,, you do that with either the pools own pump or a sump pump ,, the purpose of the hole is to give groundwater a path to get back into the pool otherwise it can float out of the ground if you have a wet spell. I have a 3hp electric jackhammer I use just for that... you want to knock a hole as close to the main drain as possible without hitting the piping and save the marcite or pebble-tec (final finish coat) to reuse after you patch the hole so you don’t have a problem matching the look.
Black algae? SIMPLE .. get tough with it ,, you have to breach the shell it builds around itself ,, use a wire brush ... then you apply chlorine DIRECTLY to the algae ,, grab a tablet and grind it into the spot.. if you have any powdered or crystalline copper sulfate grind that in too ... when you’ve killed it all (you may have to do it twice) then backwash your filter ... liquid copper sulfate is your best friend when it comes to green/yellow algae ,, if you buy it in the pool store a single qt. bottle (1 application) will cost you $20+ ,, if you buy the same chemical at Home Depot in the garden center you can get a pint bottle for about $7 that will make 8 applications when you dilute it.. just ask for fungicide concentrate and read the ingredients.