Pentair FNS Plus DE Pressure Rise

[Barkyman]

Hi.
I have a Pentair 48 FNS plus DE filter and a Pentair Intelliflo pump. After backwashing and refilling my DE I notice the pressure start rising 16- 25 now and the GPM on the pump keeps slowly dropping over the last week.

I would assume I should backwash and refill with less DE. Maybe it's a combination of too much DE and excess dirt on the filters. Chlorine is fine at 5ppm and PH is steady at 7.6-7.8 for a salt water pool.

Just wanted to see if I was off base with next steps. Thanks!

 

[PoolStored]

This is likely a chemistry problem (algae), not pump or filter problem. Do you have a test kit? Can you post your most recent test?

 

[Barkyman]

I actually have the Taylor kit coming this week. But I have been using a standard chemical test for Chlorine and PH. I have been steady at 5ppm for chlorine and 7.6-7.8 for PH. Also did the Orenda Phosphate remover about 2 weeks ago which worked great as my level is 0 now. CYA is around 50-60. Pool is crystal clear.

 

[PoolStored]

A week is really fast. What make and model number is your filter? How much DE did you put in? Might fill out your signature...

Create Your Signature - Further Reading

www.troublefreepool.com

 

[Barkyman]

I use the Cellulose Fiber which is non toxic and I like much better. My filter requires about 4.8 lbs DE, but the Cellulose Fiber bag calls for 12 8oz scoops for a 48 Filter.

I'm thinking I possibly put in too much based on the bag. Maybe I should backwash and put in less than 80%. Maybe that will work.

 

[PoolStored]

For DE, the recommendation is full load for a clean filter. 80% for a backwashed filter. Cellulose throws another wrinkle, but 80% is probably a good staring place...

 

[1poolman1]

I use the Cellulose Fiber which is non toxic and I like much better. My filter requires about 4.8 lbs DE, but the Cellulose Fiber bag calls for 12 8oz scoops for a 48 Filter.

I'm thinking I possibly put in too much based on the bag. Maybe I should backwash and put in less than 80%. Maybe that will work.

A cup like this made for DE, about 90% full of cellulose is all that you need for that size filter. Its slightly larger than a 1lb. coffee can. Takes getting used to what appears to be too little. You can adjust a bit as needed, but that is all I ever used on a filter that size while servicing commercial pools.

 

[Barkyman]

What would that be close to volume wise in OZ. The bag came with a scoop that says 8OZ at the top. It said 12 of those for a clean 48 Filter.

I have a large cup that's 32oz.

 

[Barkyman]

That is a 1 litre scoop cup. So about 90% of 1 litre or scoop for a clean filter. Then about 75% of that for a refill for cellulose Fiber?

 

[1poolman1]

What would that be close to volume wise in OZ. The bag came with a scoop that says 8OZ at the top. It said 12 of those for a clean 48 Filter.

I have a large cup that's 32oz.

I have no idea in ounces. Never bother to measure it. Cellulose came out and became available about 31 years ago. The manufacturer's rep told me the advice on how much to use and it always worked. For a 48 I used what I mentioned. For a 60 I filled it completely. For a 72 I tightly packed the cup. Never had an issue doing it that way. It made the water in high-use commercial (apartment) pools sparkle. I used the exact DE cup pictured. It is still available.

 

[Barkyman]

Great. Thank You!