How to deal with spa algae.
Hi, I'm new, and I hope this is the right forum for this question.
I have a (gunite) spa, approx 2000 gallons. Since installation we've always had a huge problem with algae. It's so bad we haven't used it for a while, but I want to get it cleaned out again.
The spa is electrically heated, so we don't keep it that hot most of the time -- it's about $40 just to get it up to temp. So usually we keep it around 55 degrees in the winter, and just turn it up when we want to use it. In the summer it stays around 85 or so by itself. There is a 'stretch type' cover but no longer a thermal blanket, it made the algae worse. Bather load is very low -- 2 people for an hour, maybe 1-2 x per month max.
Filtration is via a 2 HP pump and a 90 sq foot filter which runs 24 hours a day. There is a Delzone ZO-900 ozonator.
Water chemistry is typically 100 ppm Alkalinity, 300 ppm Hardness. ph tends to creep up into the mid 8 range, so sometimes I add muriatic acid to get it back to the mid 7's.
We use bromine, with granules in the water and extra tablets in a floater.
Any thoughts on what I’m doing wrong?
Would an UV clarifier help? (I just added one to my outdoor ornamental fountain, and it helps a lot, but if using it with the spa I'd have to do a lot of plumbing, and I want to make sure before I delve into that).
I'd like to get it really cleaned out, powerwashed, and start from scratch, but want to make sure I have a better plan than what I've been doing so it just doesn't all start over again.
Thanks for any suggestions.