Running DE filter without backwash valve

[centralphoenix]

Hello,

I have a Pentair FNS40 Plus. I want to relocate my equipment and was wondering if I really need a backwash valve on this thing? I am going to be honest - I never backwash anyway and just take the entire filter apart 1-2 a year, wash it and replace DE. Never had any issues with algae etc.
I read in this thread that the Quad filters don't need a backwash valve, but I also understand they are built a little differently. I also read recommendations that filters should be backwashed weekly. This sounds crazy to me - what is the purpose of frequent backwashing like this?

Thanks!

 

[Lake Placid]

You need an MPV if you have a DE filter. Those recommendations are wrong. 25% over clean pressure is when you should backwash. Often times service companies just backwash on a routine schedule so they know it’s done. It’s a waste. Where are these “recommendations” matriculating from?

 

[centralphoenix]

I found/heard the recommendations in various places - here, reddit, pool store.

My filter clean PSI is around 10 and after the entire season when i was disassemblying it for cleaning it was around 11-12 so below your 25% recommendation.

You say I need the valve, but I still don’t know why I would need it. I would understand if I had to do it weekly, even monthly, but to do it once a year seems like a waste of plastic…

 

[TinFoilHat]

I would be very surprised that you could run a DE filter for an entire year and never need to backwash once. We get dust storms you know. Obviously it helps that you take it apart and clean it two times per year and that along with perhaps a very large DE filter could be the explanation. But yet, an MPV valve could be just what you need to avoid one of those teardowns.

 

[Lake Placid]

You say I need the valve, but I still don’t know why I would need it.

1. You get algae and need to backwash more than you think.
2. An internal part in the filter breaks and you need to put the mpv in recirculate to bypass the filter but keep the system running.
3. You get a lot of rain and want to bleed off some water to get the pool back to normal operating levels, so you pump to waste.

Just 3 quick examples but there are more….Your money your choice.

 

[Jimrahbe]

CP,

I had two rent houses that had DE filters with MPVs.. I too never backwashed, and just took the filters apart twice a year... I bet I could have gone a whole year, as the IntelliFlo pumps ran at 1200 rpm most of the time..

Both MPVs started leaking, or being really hard to turn, so I just removed them.. I ran them that way for 3 or 4 years, without any problems at all.. I recently changed to large cartridges filters and will Never, Ever, go back to DE...

The "recommendation" to clean or backwash your filter at 25% over clean is just that... A recommendation.. it is not an absolute!!!

At my house, I have a large cartridge filter that I clean once a year.. At my normal operating speed of 1200 RPM, my filter pressure is about 1 or 2 lbs. and even after a year usually about 3 psi.

Thanks,

Jim R.

 

[centralphoenix]

I would be very surprised that you could run a DE filter for an entire year and never need to backwash once. We get dust storms you know. Obviously it helps that you take it apart and clean it two times per year and that along with perhaps a very large DE filter could be the explanation. But yet, an MPV valve could be just what you need to avoid one of those teardowns.

I have a robotic cleaner, so most of the dust/dirt doesn’t go into the filter. I also use filter basket socks which catch most of the dirt/sand along with bigger matter (i change those weekly)

1. You get algae and need to backwash more than you think.
2. An internal part in the filter breaks and you need to put the mpv in recirculate to bypass the filter but keep the system running.
3. You get a lot of rain and want to bleed off some water to get the pool back to normal operating levels, so you pump to waste.

Just 3 quick examples but there are more….Your money your choice.

I see your points and I bet they are valid for most of the country. However, I live in the dessert and don't get a lot of organic matter in the pool, so algae are not as big of an issue as I bet they are in Missouri and pretty much in 90% of the country. Similarly, I have never had to empty my pool after it rained. As a matter of fact, water evaporates so quickly here in Phoenix, that I invested in an auto-leveler because I was sick of constantly adding water.