I have a question, but haven't figured this site out totally yet. why , if the impellors arent clogged and i have good flow in a de filter, would I only get about 7 lbs of pressure? could it be too little or too much de?
Here at TFP there are many different topics where you can post your questions. This particular question you ask is related to our topic section called "Equipment - Build, Use, and Repair". In that section there is a subsection called "Pumping Station". You get to the topic section by going to the main TFP website. At the top you will notice a white bar and in that bar is a link labled "Board Index". Click on board index and scroll down a bit and you will see the sections I am refering to. You can ask this question there if you wish or wait till a moderator comes along and moves your post. It won't take very long.
I'm using Aqua Pearl, similar to DE but without the silica, in my big Quad filter, 80 sq ft. It is backwashing out better than cellulose did. When I backwash and run pump on the usual, 19-20 gpm, which is pretty low flow, after backwashing the psi is 3-5. When I take filter apart and clean, it is just a little under 3. If I increase the pump speed psi is higher than that and goes up as I run the pump faster. Any of the three common filter media for a DE filter, cellulose, DE, or Aqua Pearl, all give a just below 3 psi when the filter is opened and cleaned when filtering at 19-20 gpm.
I'm not sure what the ball park figure would be in terms of comparing the 10-20 gpm to a certain HP, and/or fixed speed pump. I do not have very high head on the system.