Assuming I follow the method described in http://www.troublefreepool.com/conte...-a-sand-filter and I use pool DE, do you think it's OK to add DE to my recycled glass media filter? Background follows.
CYA 70 (estimate based on amount added, pool volume, and losses due to backwash and drain down)
CH 285 (PS test at 160 plus addition of CaCl)
Salt 4000 (similar estimate, SWC manual says 4000 and low-salt warning light is off)
When we first started the pool, lots of cloudiness from the build. It took about two weeks to get it sparkling, using clarifiers including polychite, poly-diallyldimethylammonium chloride, and aluminium sulphate. Through the same period I tried different pumping speeds, and noticed that after the coagulated bits were gone, very little further clarifying happened on high speed (around 50 gpm). Low speed worked best (around 32 gpm).
A theory developed in my newbie mind that the really fine stuff was going right through the filter. I tested switching the pump to high and watching the returns with the SWC off, and thought I saw a bit of white, but can't really be sure of that. Using low speed for the most part, it was sparkling clean for the next 2 weeks. The pressure gradually rose, and once I got above ~12 psi on high, I could use any pump speed I wanted.
Then a very heavy rainstorm (7 inches) and a bit of fiddling getting the water back in balance.
My high speed clean pressure is 10 psi. When it reached around 13 psi, I backwashed using some of the excess water from the rain, and it ran clean after 1.5 minutes. I rinsed until it ran clean (around 45 seconds) and went back to filtering. I could see white clouds coming out the returns, so I stopped filtering (as quick as I could) and re-rinsed for 2 minutes. No more cloudy returns, but the pool was marginally cloudy (could still make out the beads on the bottom, but just not sparkly like it was).
Then we had a long hot (and very fun) pool day with 6 kids and two adults. A bunch of grass clippings and a rashie ended up in the skimmer box, and I got my first whiff of chloramines when I took it all out. I added an extra 1/4 gallon of trade chlorine for each of the next two days and kept the pH as close to 7.8 as I could, but the pool got cloudier. I could still see the bottom, but it got harder to focus on individual beads in the finish at the deep end (6'). I used medium speed (around 45 gpm) for 24 hrs trying to get the cloudiness out, but no noticeable progress. Slowed the pump down to low again, and after about 12 hours it's good enough to invite people over! Not perfect yet, but as good as most pools.
The recycled glass seemed well processed when we put it in. Size was roughly that of granulated sugar, maybe a tiny bit larger. Could sift it through your fingers with almost nothing sticking. No shards certainly. Multi-coloured and smelled mildly like stale beer. From what I've read here, I would use sand next time, but it was same price as sand and I had heard only good things at that point in time.
So, any reason not to add a bit of DE to help the recycled glass catch the fine stuff?