This year I am trying to add in Borax to increase the borate level of the pool. I choose a slow way of doing it, adding several box of borax per day and use muriatic acid to balance any PH change. I tried different ways of adding in Borax. Based on the pool calculator, pour in correct amount of acid first, and wait for 30mins. 1st way. try to dissolve the Borax powder in a bucket of water as much as it can, then slowly pour it into the skimmer. 2nd way dissolve and pour it directly into the pool. 3rd way, pour the powder directly into the skimmer. No matter how I did it, after a short time period, (<1 day) the DE filter pressure increases by 10psi (from 20 to 30psi) and no water flow from the return line any more. Whenever I see it happens, I shutdown the pump, let it idle for several minutes, then restart the pump. Again, at the first several minutes, the water flowing back from the return line and after a while, no return flow again. In this case, I am forced to do backwash or open the filter to clean.
This really bothers me a lot. I searched online, seems like nobody ever had this issue before. My theory, which may not be correct is that Borax cannot be fully dissolved, since I always see there are very tiny crystal residue which cannot be dissolved in the water. These crystals clog the DE filter and I have to keep backwash it after this happens. btw, I started from a very clean grid (water cleaned and submerged in 1:6 muriatic acid for 18 hours. so it shouldn't be the filter issue.)
I don't know if anyone has the same experience as mine. Does my theory make sense? finally, What's the best way of adding in borax without clogging the filter or it cannot be avoided at all?