I have a large pool in Mexico ( 39,000 galls ) that is filled with well water and we have extremely high water temperature for 8 months of the year ( up to 94 degreess F in mid summer )
In addition to my DE filter ( 36 sq.ft.) I also run the incoming water from the well through a series of external filters when I initially fill the pool and when I add water after backwashing or waste out.
The well water is hard and contains sulhur and ( I think ) iron.
The first external filter consists of layered media to filter out the impurities and then the water goes through a second filter
( water softener granules ) to soften the water.
Here's the problem ........ I use tri-chlor tabs ( multi function ) in a floater plus an occasional tab in the skimmer to disolve faster aand I shock periodically but although my chlorine levels are fine, the Ph is always high... 7.9 to 8.0.
Second part of the problem is that my DE filter goes to high pressure within 12 hours of a new re-charge ( 5 coffee cans ) Backwashing will get the pressure back to normal for about 8 more hours and then after each backwash it takes less and less time before the pressure rises again. I add 1 can of DE after every 5th backwash but within a week the grids have to be removed from the filter and cleaned with a water/muriatic acid solution ( soaked overnight, then hosed off and soaked again for 4 hours and then hosed off again before being put back in the filter )
When I open the filter to clean the grids, they are completely caked with a brown colored mud ( hence my belief tht there is iron in the water ). Althought the grids are clean, they are beginning to feel somewhat brittle and I think trhey have reached the end of their usefull life. When I return to Mexico next month I am taking back a brand new set of grids.
Questions: .... 1) does anyone have any idea why my Ph is always high 2) What is causing the brown colored mud to collect on the grids and also stain the walls of my pool slightly 3) I am trying to find out if anybody makes a metal sequesterant for iron in granular rather than liquid form that I could add to my layered media filter, to catch the iron before it even enters the pool..... I could also add liquid sequesterant in maintenance doses directly to the pool water.
Remember.... the extremely high water temp. probably has a lot to do with it and also after a heavy rain the pool turns green and I have to start from scratch to get it reasonably clean again
All suggestion are appreciated