My new FNS Plus Vertical Grid DE Filter came with no instructions on how to backwash. Where can I find a step-by-step?
For instructions on backwashing and other trouble shooting, you need an Owner's Manual. You can find one online at the following link:
http://www.pentairpool.com/pdfs/FNSPlusVerticalGridDEFilterOM.pdf
The way you backwash this filter is easy once you get the hang of it!
The first thing you will do is turn off the system, change the valve position to the Backwash position. If you have a Multiport Valve, you will press down on the handle and spin it so that the knotch is pointed to BACKWASH. If you have a Slide Valve, only has two positions, up and down, you turn the handle so that the metal pin is out of the holder and move the handle in the opposite direction. You will need to turn the handle to lock the pin into position.
Once this is done, you will turn on your pump. Pentair recommends that you backwash for 1 minute, then turn off the pump.
If you have the Slide Valve, you will put it back into the FILTER position and then turn the pump back on for 1 minute. If you have the Multiport Valve, you will put it in the RINSE position and then turn the pump back on for 1 minute.
Pentair recommends that you do this cycle a total of three times, backwash/rinse, backwash/rinse, backwash/rinse. AFTER the third time, you will need to open the Air Release Valve at the top of the filter while the pump is OFF and the valve position in back on FILTER. Once this is done, turn on the pump. When you have a steady stream of water coming out of the Air Release Valve, close that up. This way you have no air in the system.
Now, you will mix your DE "Slurry" in a bucket. Depending on your model of filter, you will measure out your DE and mix with water to the consistancy of milk. **IF it is just a backwash, you will only add 80% of the original amount of DE. You only add the total 100% of DE when you completely take the filter apart and clean it out.**
You will slowly pour the slurry into the skimmer that is closest to the pump. This will allow the DE to evenly coat the grids in the filter. Wait about 5 minutes and then check the pressure gauge on the filter. Once the PSI reaches 8 to 10 PSI above this number, it is time to backwash.
I would like to add to Delita's awesome instruction - I'm sorry, but it is a slight correction if you will... Every thing stays the same except for owners of a Multiport Filter Valve. After the allotted time for backwash, the Rinse should only be 15 to 30 seconds, maximum. Anything more is useless, and a waste of water, especially for the drought stricken states.
And yes, the combination of three times for a diatomaceous earth filter stands just as Delita's stated. But it's only one cycle for a backwash time of approximately 2 to 3 minutes, for a sand filter.
A little trick to measure proper amount of DE...
Blue Devil B8300 Rake Scoop with Handle
IF you like to know all about your filter, then that can or cup holds enough to charge 5 Sq. Ft. Of filter. So a little more than 7 cans/cups will suffice. 7 cups x 5 Sq. Ft. = 35 Sq. Ft.
The he reason for the 80% rule = you never get all DE out when backwashing, 20% stays behind. You Don't want to OVER charge your filter.
Good luck.
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Thank you so much. I wasn't able to find backwash instructions in my hard copy of the manual because the manual is so difficult to decipher. (Every other sentence is to read another section and it uses its own lingo instead of common usage terms like backwash.)
I downloaded the (older) version of the manual you located and searched for "backwash" and lo and behold the word showed up all of once, in the middle of a detailed instruction. No wonder I couldn't find backwash instructions. Moreover, there was no mention of RINSE let alone "backwash/rinse, backwash/rinse, backwash/rinse", etc., so I am really appreciative of your step-by-step instructions. The installer walked me through the process once but it was just verbal and I needed something written. Your instructions are great.
Do you always have to add DE everytime you backwash??? I thought it just cleaned the filters and you didn't have to add DE except when you take the whole thing apart! Jeeezzz I hate my pool!
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