A year ago my pump went out and I replaced it with an A.O. Smith B130 2.4hp.

[pool007]

A year ago my pump went out and I replaced it with an A.O. Smith B130 2.4hp. I believe my old pump was a 2hp. I have a 14K pool with 2 skimmers, a fountain in the spa that flow like a waterfall back into the pool and a sheer decent feature.

Also went the pump went out it collapsed a lot of the DE grids. I replaced all the grids. Now I noticed after a couple of month that a couple of grids are collapsed again and I constantly have low pressure issues.

After I replaced the pump and grids I had 20psi. When I have low pressure in the pool issues it is up to 30psi. I can back wash and I am back to 20psi.

Any ideas on the grids issue?
Thanks
Steve

[PoolDoc]

Yeah, it sounds like you are over-pressuring, and then collapsing them. The explanation is one most people find complicated so I'll hold off till I can confirm. And, to do so, I need to know what PUMP (not motor) and filter models you have on your pool.

Just as an FYI, If I'm right, you'll need to plumb in a filter bypass, or else a valve you can use to restrict flow.

Ben

[pool007]

thanks PoolDoc
Aqualink rs4
Hayward DE2420L Filter
AutoClear salt system



Also what if I put in some sort of bag filter? That way I can cut down on how often the DE filter needs cleaning and reduce the pressure?

[PoolDoc]

The DE2420 is a 48GPM filter. The AO Smith B130 is a true 2 HP motor. (The Aqualink RS4 is a controller, and not a pump or a filter).

But, regardless of what pump you have 2HP is way, WAY too big for the DE2420. Assuming that you have a pump that can use a 2HP motor efficiently, you should either
+ install a bypass to carry 50 to 70% of the pump output, OR
+ replace the filter with a DE6420 (120GPM filter). Given that you probably need to gut your existing filter, this might be a good option, since it would allow you to have the flow you need for all your water features.

Alternatively, depending on what pump you have, you might replace your existing impeller/diffuser with a 1 HP impeller/diffuser set. Your 2HP motor will run OK against a 1HP load, and will stop blowing your filter apart.

CAUTION: if you NEED high pressure flow for some of the features, you may need to split your piping into a normal pressure filter & circulate loop, and a high pressure water feature loop.

Ben

[pool007]

Update, when I start to lose pressure from the fountain, my filter reads 33psi.

Also the motor filter basket is not completely filled with water. There is an air gap. Maybe an inch. So I can see air in the motor basket but this does not happen for maybe 6hrs of the motor running.

So if I turn off the pump, wait maybe 5min and turn back on, we are back to 20psi and the fountain has pressure.

[PoolDoc]

Not sure any of that's relevant.

Still need to know which pump you have, to be sure, but it's very, very likely you are over-pressurizing the filter. If you are reaching 33+ pounds with dirty DE membranes, you've got a 25+ pressure differential across the membranes . . . and most DE grids won't support that kind of load. To put it another way, on a 2420, you have 24 sft of filter area across 7 full size and 1 short membrane grids or elements. Figure 3 sft each (1.5 on each side) and you are asking the grids to support 3 x 144 (sqin / sft) x 20 lbs/sqin OR 8600 lbs. That's roughly like asking a grid (if it was flat instead of curved) to support the weight of a loaded dump truck tire driving across it.

Not happening.

Sounds like whoever designed your water features may have been shooting from the hip, rather than actually designing the flows and hydraulics of your system. That works when it works, but when it doesn't, well, it sucks. That's one reason many builders put in multiple pumps -- it makes the design problem MUCH easier.

I'm pretty reluctant to give too much advice, because without a piping layout drawing, and full hydraulic data on each element (spa, fountain, "sheer decent" feature (not sure what that is) and pool) it's not really possible to actually calculate the relationships among the elements.*

But, I'm still safe in saying that a 2HP pump is WAY too big for a 24' DE filter. That's where you need to start; anything else is just tweaking around the edges of the problem.

Sorry,

Ben

* Just to be clear -- I'm not offering to redesign it. It's time consuming and still risky without on-site inspection.

[pool007]

Update, when I start to lose pressure from the fountain, my filter reads 33psi.

Also the motor filter basket is not completely filled with water. There is an air gap. Maybe an inch. So I can see air in the motor basket but this does not happen for maybe 6hrs of the motor running.

So if I turn off the pump, wait maybe 5min and turn back on, we are back to 20psi and the fountain has pressure.

http://i112.photobucket.com/albums/n...ol/Picture.jpg
http://i112.photobucket.com/albums/n...Picture028.jpg
http://i112.photobucket.com/albums/n...Picture029.jpg

[PoolDoc]

Wow.

It's hard to believe the guys who did this:






also did this:




Great looking pool. Hydraulic design? Not so great.

Has anything changed in the last year or so? What I'm trying to get at is this: has the pool ever worked really well in it's current configuration?

Is that 2" or 1.5" pipe?
Is that a Sta-Rite pump? Which model?
Are you using Baquacil?
(Your water looks a bit sudsy -- which Baquacil (Softswim, Revacil, etc.) can do. Baquacil will definitely plug a DE filter.)

But, have you talked to the guy who built that pool? If anyone knows how to trouble shoot that piping system, he does. I'm thinking he's the guy who knows how to get it to work best.

Best wishes,

Ben / PoolDoc