First of all, this forum has been invaluable to me. I have read many threads and taken much advice. In fact, my TFT100 chem kit came a few days ago. I'm on my way to a TFT PhD...
Background: I have owned pools and spas in FL in the past. My pools have all been easily accessed DE filters with auto-chlorinators and a Polaris cleaner. I rarely had problems except for one nasty bout of black algae. Shortly thereafter I has the marcite replaced/covered with fiberglass and all was excellent.
I now live in the Dominican Republic and rent a house with a pool. Construction here is not like the states. The pool particulars:
-15,000 gallons, rectangular freeform shape, 3' to 5' depth
-Sta-Rite T200b sand filter/valve in an underground room with poor access (I know this is a poor quality/performing unit)
-2.5hp (I think) electric motor
-Concrete construction painted with white walls and blue bottom, both painted with deck/pool paint
-2 skimmers (one 1.5" higher than the other), one drain, 7 jets
This is a rental house and I have no intention of changing anything. When I build I would definitely build a much different set-up. Additionally, supplies beyond chlorine tablets, algaecide, "clarifier", muratic acid, soda ash & bottled chlorine cannot be found here. I had a simple chlorine/ph test kit.
My story: until 5 weeks ago the pool was spotless. I did pay for some technicians to come out and change the sand in the filter (with...get this...construction sand, not fine sand. There is no fine sand available for pools) and repair two pipes into/out of the valve. I did routine maintenance as the landlord asked; one item was backwashing for 15 seconds (more on this later.)
5 weeks ago the motor froze. I had our electrician come out and take the motor away for repairs (things are not replaced here, they are repaired.) That took 10 days to fix and reinstall, during which time I got a major green/yellow/brown algae bloom. I put a ton of chlorine and algaecide in the pool and did my best to circulate some water around. But it got ugly.
When the motor came back, no matter how long I ran the pump/filter the water would not clear and the chlorine & ph went all over the chart. I was frustrated while chasing it up and down. I filtered the **** out of the pool. And when the pump was off, the water stayed almost brown and a lot of dead algae was on the bottom. No matter how many times I vacuumed the bottom, it would blow back in, settle on the bottom and cloud the pool-you could not see more than 2.5' into the water...and it was a greenish-brown color.
Praying to the Innerweb Gods, I found this site and "did a f@<k!ng search" (DAFS). I learned the chemistry is all wrong and the backwashing needs to be 3 minutes and NOT 15 seconds.
I eventually bombed the **** out of the pool, added a bunch of soda ash and ran the filter 24/7 for a couple of days...and the water slowly started cleaning.
But when the pump was off, the dead algae would settle to the bottom, I'd vacuum it out...and it would just get blown back into the pool.
I finally decided to add an extra 3" of water to the pool, set the valve on "discharge", blocked one skimmer inlet...and vacuumed the pool, where the algae was blown out as discharge. Not filtered, but removed.
It worked. A little algae came back, so I repeated the process: more water, vacuum the bottom with the valve on discharge.
I can only assume the algae was too small to be mechanically trapped in a bad sand filter, and sucking it out bypassing the filter into the field next door worked. The numbers are now more normal and stable, the water is now almost perfectly clear, I'd say 95% where I like it, not perfect but a massive improvement...but I don't want it to go back.
My TFT100 arrived and here are my latest numbers:
Some of these values just ain't right, and I'd like to get them as close to within range as I can...and keep them there. I ask the community for suggestions, tips and advice on how best to fix the numbers and manage this pool.
Again, thanks in advance for the help. I intend to make a contribution to TFT because it has already been a money and frustration saver.