Time for A New Filter?

Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
Before spending $1,000 for a new filter (I'd do the installation), I thought I'd run it by the experts to see what you'd do.

First, it's a Pentair Tr100 Triton II and is likely 25-30 years old. (Bought the house 6 years ago.)

Second, I've been getting sand in the pool for the last couple of years, but this year it's gotten worse. So I'm thinking broken lateral. We did carefully change the sand in the filter last year.

Third, the pressure in the system is about 6-7psi @ 1500rpm, and 12 @ 2200rpm. However, and I don't know if it's related to the lateral in any way, after slamming last week and passing all tests, and the water being really clear since, it seems that every couple of hours the pressure gauge drops to almost zero. After a while more the flow is impeded, the waterfall from the spa slows down. Once I backwash, the pressure goes back to 6-12 depending on the speed of the pump. Since the pressure is supposed to go up when backwashing is needed, why would ours be going down?

Also, minor issues.... it has a slight leak from one of the pipes that goes to the multiport valve, and it's been tightened as much as possible. Not a huge deal, since it's a slow leak.
And it leaks from the top lid no matter how tight it is and even with lube and a new o-ring. Also not a huge deal, since it's pretty minimal and only happens at high rpms and when the pump is starting.

Thoughts? I could first open it up, empty it out, and see how everything looks, or do these filters have a life expectancy?

Thanks for your input--
 

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Roscoe

Well-known member
Jun 3, 2020
59
Southern AZ
My Triton II sand filter started to "bleed" water from the tank after 18ish years but I live in the desert. Are the slide valve O rings need to be replaced? I can't answer some off the input questions but thought I would bump it.
 

Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
My Triton II sand filter started to "bleed" water from the tank after 18ish years but I live in the desert. Are the slide valve O rings need to be replaced? I can't answer some off the input questions but thought I would bump it.
Hey Roscoe-- I had to look up what a slide valve is :) It has a multiport valve which is new as of last year when I rebuilt all the plumbing. So no slide valve.
 

hum2

Member
Aug 23, 2018
17
Surprise/AZ
Pool Size
14000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-30
From everything I've read if the tank itself is sound (not rusting mainly) you can part out everything else pretty easily. It's really strange that the pressure is dropping and is repaired by backwashing. Maybe there is a piece of debris that is large enough to block the flow and it gets dislodged when you backwash but then moves back to block when the pump is running?

I really want to get rid of my slide valve. If you could post a photo of your multiport replacement, I'd appreciate seeing what you did.
 

Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
From everything I've read if the tank itself is sound (not rusting mainly) you can part out everything else pretty easily. It's really strange that the pressure is dropping and is repaired by backwashing. Maybe there is a piece of debris that is large enough to block the flow and it gets dislodged when you backwash but then moves back to block when the pump is running?

I really want to get rid of my slide valve. If you could post a photo of your multiport replacement, I'd appreciate seeing what you did.
Hey Hum-- I don't know about the problem being a piece of debris. I think--but am not sure--that maybe it's gotten better. But still, the same thing is happening with the diminishing pressure and flow until I backwash. I'm going to open the filter and look in to see what I see. I'm leaning toward trying to replace the laterals, but I'll put up another post on this board to see if I get any expert answers.

In terms of the multiport, here are some pics. (Notice the leaking filter, even though I changed the o-ring, silicone, and tightened it.) I love the multiport compared to the slide valve. But if you switch, you'll have to redo your plumbing to make it work. I redid all my above-ground plumbing and valves last year, so while I was at it I put in the multiport. When I installed it, I put in a piece of clear PVC pipe between the multiport and the backwash/rinse valve so I could get a good look at the water while backwashing/rinsing. I remembered my dad's pool decades ago had that and I really like it.

Just found that my chlorine generator is shot. So the fun never ends when you have a pool!
 

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JamesW

TFP Expert
Mar 2, 2011
28,291
Yours says for FNS and FNS Plus, which are DE filters.

It should look like this and say for Triton or Quad DE.

Backwash should be away from the filter and Filter should point to the filter.
1623556989587.png
 

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Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
Can you show the pipe from the pump to the multiport?

Does the pipe from the pump to the multiport go into the top hole of the multiport?
Well, that's an unwelcome, but needed revelation! Here are some pics that might help.

Yes, the pipe from the pump to the multiport goes into the top hole of the multiport. And looking at the description of the multiport I bought, it is as you said "For use with FNS, FNS Plus DE Pool Filters." Here it is:


So it looks like I've got another job ahead of me. James, would this explain the sand in the pool and spa from the returns? If so, I hope I can get away with not replacing the filter too.

Thanks so much for taking a look--
 

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Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
Yes.

You are basically running in backwash mode all the time.

In backwash mode, the water goes into the laterals and then up through the sand, which lifts sand and puts it in the returns.
So happy to be finding this out now! Thanks again.

I'll order a new 261055 and get the new plumbing sorted out ASAP. I've been running it like this since the end of last season. Even did a successful SLAM a month ago. But it wasn't quite right, of course. I'll ask the pool supply company about this, but the ports on these two multiports all line up in the same place, correct? My fingers are crossed on this one, since I'm hoping I can just do whatever plumbing is necessary to switch two identically plumbed multiports, rather than reconfiguring the plumbing lines.
 

JamesW

TFP Expert
Mar 2, 2011
28,291
Be aware that the laterals might be clogged or damaged because the pump has been sending dirty water directly into the inside of the laterals.

It might begin to work ok with a new multiport, but there might be issues that won't be apparent until you run the pump with the new multiport.
 
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Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
Be aware that the laterals might be clogged or damaged because the pump has been sending dirty water directly into the inside of the laterals.

It might begin to work ok with a new multiport, but there might be issues that won't be apparent until you run the pump with the new multiport.
Got it James. I'll ask your opinion on my original post. Given the filter's age/condition, what's your opinion on keeping the old filter, or replacing that too?
 

JamesW

TFP Expert
Mar 2, 2011
28,291
It's a good filter that can last for decades, but the stress on the laterals might have caused issues.

It's really a judgment call if you want to try a new multiport or just replace the whole thing.

I would likely go to a 420 square foot Pentair Clean and Clear Plus cartridge filter.
 
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Earthman Bob

Bronze Supporter
Mar 25, 2019
108
Long Island
Pool Size
36000
Surface
Plaster
It's a good filter that can last for decades, but the stress on the laterals might have caused issues.

It's really a judgment call if you want to try a new multiport or just replace the whole thing.

I would likely go to a 420 square foot Pentair Clean and Clear Plus cartridge filter.
James--thanks again for the detective work. I'd be totally focused in the wrong direction if you hadn't spotted the issue.

I'm strongly leaning toward a new filter at this point. I've been reading a whole lot about cartridge vs sand, but am still on the fence. I really like the pool water saving of cartridges, but don't like the $$$ you have to put into it every few years to replace the cartridges. And the cartridges are not cheap.

I read here that to size a cartridge filter is 200SF/10,000 gallons of pool volume. So if I went that way, I'd have to go with the next step up from the 420. I'll keep on reading...
 
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