Cleaning algae with a new cartridge filter

[PoolDoc]

Ideally, a cartridge filter should be operated around 0.4 GPM/sft. This is the commercial pool rate . . . which turns out to be the real 'works well' rate for all 3 filter types. This would mean a 20 GPM flow rate for a 50 sft filter. That would give you an 8-hour turnover rate of 20 * 60 * 8 = 9600 gallons, which is OK for your pool.

On the other hand, with a cartridge filter, there's no downside, other than cost, to massively oversizing your filter (you can't do this with DE filters, or especially, with sand filters, which need 15 GPM/sft to backwash properly). So, if you want to reduce filter cleaning frequency, and increase water clarity, you could go with a 100 or even 200 sft filter, and not have any problems, except $$'s of course.

However, for several reasons, if I were you, I'd probably opt to go with a 100sft filter (or else, a 2nd matching 50 ft filter) and have a new spare for each filter, which I would keep in a cleaning solution, so that I could always swap a completely cleaned cartridge for my dirty one.

[waterbear]

I second the 100 sq ft filter on a pool your size! (And having a clean spare cart on hand to swap out!)

[RMA127]

Thanks. I have noticed that since i have the water quality in better shape(no algae, good Chlorine Levels) that the cleaned filter(6 months old) goes in and starts at 24PSI, then within 8 hours it is up to 30PSI. I take the filter out and wash it with the garden hose and notice that it is not really that bad(dirty). I know that this can't be normal as the pressure coming out of the jets does diminish quite a bit when it is running at 30PSI. When it is at 24PSI the flow is good and strong, but as i said within 8 hours or so, it jumps up to 30PSI and pressure is diminished. I am going to order a replacement filter but i suspect that i just need to get a bigger filter, like the 100sqft one mentioned above and hopefully the time between cleaninigs will be less. My old 50sqft filter used to last 1 to 2 weeks between cleanings, this Hayward although the same size(50sqft) just does not match up. The old one was the Sta Rite 50.