Pool problems on startup

[michael3]

Hey stma, I just got my shut off valve installed between my pump and filter, dropped my psi from 17 to 10 and water flow slowed alot, gonna run it till I see improvements lol, will let ya know

[stma]

@Ben/ WaterMom>>>> Foolish question of the Year::: Could I use "Food Grade" DE for my 1/2 Cup needs ?? ( I can purchase way less quantity at a cheaper cost than the Pool-store DE )..

[PoolDoc]

You can try. If it doesn't shoot back into the pool, you can use it.

[stma]

Hey Ben:: I did receive the DE (for pools) today... I applied as per Carl's directions. In the event this does work, Should I see a difference in the cloudiness pretty quick ?

[PoolDoc]

Hey Ben:: I did receive the DE (for pools) today... I applied as per Carl's directions. In the event this does work, Should I see a difference in the cloudiness pretty quick ?

No. Here's why:

A sand filter filters in depth, capturing debris in the first 4 - 12" of the sand. If you think of each 1/2 layer of sand, then a 3 square foot filter (24" diameter) filtering with the top 6" of sand would have a total filter area of 3 sft x 6" x 2 layers/inch = 36 sq. ft of filter surface.

By contrast, a DE filter works by filtering on the surface only.

This is why a sand filter has an effective flow rate for good filtration of 15 gpm/sft, but a DE filter has a flow rate of 2 gpm/sft. Thus a 3 sft sand filter can handle a flow of 45 GPM, but a 3 sft DE filter can handle a flow of only 6 gpm!

What happens when you add DE to say, an 18" sand filter, is that you convert a filter that can handle 25 gpm, to a filter that *should* handle only 3.5 gpm. It *will* handle more, but at the price of stopping up very, very quickly.

I suppose in theory, if you fully coated a sand filter, and then backwashed it several times per day, you could clean up a mess like your quite quickly. But most people don't do that.

ALSO . . . some of the particles in badly clouded pools seem to be too fine for even a DE filter to handle quickly -- it make take multiple passes through the filter to get everything.

[stma]

I have the next few days off and have ZERO problem fully coating and backwashing.... Could you define "Coating" ?? I have 12 pounds of this stuff and the quicker I see bottom, the happier my life will be !!!

[PoolDoc]

Probably 3 oz by weight per square foot of sand surface. (1.8 sft for 18" filter; 3 sft for 24" filter)

[stma]

Just thinking out loud here, I would need to "coat" after every back wash ??

[michael3]

Stma, I just got home with new sand and a 24 lb box of DE lol, pretty excited to get everything back together, of course there calling for severe storms here this afternoon. Maybe both our pools will clear at same time lol