From reading the Adding DE to sand filter article, it sounds like you add DE each time after you backwash. I'm guessing after you do this its normal operation of the sand filter. ie you leave the DE in there until your next normal backwash (when the pressure goes up by 8-9psi) Is this true?
Also, to complicate things, I used a cellulose alternative. The package says you should backwash after 48hours. Has anyone had any trouble leaving it in until the next time you need to backwash? Like you would with the DE above? Since you use this as a DE replacement, I can't imagine there would be a problem leaving it in longer like you would with DE. I'm guessing is that is suggestion, due to the fact the pressure can build so quickly. I just want to be sure, and see if anyone has any experience with this.
For some background: I don't have any water issues. Its clear, and water chemistry is good (FC6 CC.5, PH 7.6, CYA 40, TA100, CH 50 Borate~60, Salt ~2000 Temp 58F). Kinda got sparklypoolitis over the summer, I had very few problems (had a mechanical failure I had to deal with), just trying to eek out a but more sparkly out of the pool.
The Cellulose alternative seems to be working, its been about a day and the pressure has gone up about 3psi, it was a little dark this morning before work so I can't comment on any water clarity improvements. One thing that surprised me was how much alternative it took. The article says 1-2 cups of DE. The packaging had a volume per ft2 listed which came to about 12-13cups for my filter, I ended up using about 13cups to get a 1 psi rise.