First encounter with DE Filter

[Mike_in_NJ]

A DE filter is similar in operation to a sand filter, except that instead of semi-permanent sand as the filter media a DE filter uses replaceable DE as the filter media.

When you backwash a sand filter, you are running the water 'backwards' through the filter and pushing the gunk out of the sand and out the backwash pipe/port. The sand stays in the filter (hopefully).

When you backwash a DE filter, you are running the water 'backwards' through the filter and flushing the gunk and the dirty DE out the backwash pipe/port. After you are done backwashing and reset the valving for 'normal' operation, you then have to add new DE to the filter.

If you're OK with the start-up of your old sand filter, you should be OK with starting up the new DE system. Just remember that the filter isn't filtering until after you put the DE in.

On my DE filter, if the filter is not filled with water, I'll open the air bleeder valve manually when I start the pump until I get some water into the top of the filter tank and out the bleeder valve. I'll close the bleeder valve at that point, let it run for a little bit (30 seconds, a minute, whatever) and then reopen the valve again and 'burp' out a little more air. After I have water flowing 'normally' through the pump/filter/pipes for a few minutes, then I add the DE into a skimmer.

Do you need anything else? Remember that the DE is just the filter media, the rest of the pool chemistry still has to be taken care of as usual. Bleach, borax, baking soda, acid, whatever.

[gkrupkin]

Thanks for all the help. I successfully opened the pool today. My psi on the filter is currently at 4. Is that normal, or does it seem a bit low? I've got plenty of water in the pool, the return pressure seems normal. I've already added about 7 cups of DE "slurry" to the skimmer.

[Mike_in_NJ]

7 cups of DE, as in seven 8-ounce measuring cups??? Way too little DE.

There should be a label on the filter saying how much DE to use. A 36 ft2 DE filter usually should take about 3.6 pounds of DE. An empty 'pound' coffee can will hold about 1/2 pound of DE powder, so you'd need 7 cans full of DE to get your 3.5 pounds of DE (close enough to 3.6 pounds).

As to the pressure, maybe your pressure gauge is NG and needs to be replaced. Or you don't have to valving set properly and you are starving the pump of water and hence have a very low pressure. Or you have a suction-side air leak and hence have low pressure. It could be many things, or maybe that is just the pressure that your clean filter runs at.

[chemicalbalance]

1. Dont guess how much DE to use. The DE box will tell you exactly how much to use. Just put that amount in a bucket. Add some water to make a slurry and dump it in the skimmer. The slurry will coat the filter. Once you do this and let it run awhile, you can shut the pump off, remove the filter cover and visually observe that the DE is coating the filter like white mud. There shouldnt be any screen visible. Its really pretty simply and fail proof. You wont screw it up.

2. I do not rely on the pressure guage on the filter to tell me when to change the DE. I have found that my filter can be totally clogged and the pressure guage doesnt move at all. (And I am an oilfield engineer and I replaced my cheap pressure guage with a high quaility industrial brass one -- its not the guage.) I have found that when my filter is new, the return line to the pool is very strong -- like a jacuzzi jet and my vacuum works great. When my vacuum doesnt pick up or the kids complain that the return jet in the pool is weak, I know its time to change the DE. I have found that changing the DE every month works very well. Some people say that you can let it go almost a season, but I like strong filtration. Its your preference.