replumbing, help me pick filter size please

[jcverheijen]

Hi,

new to the forum. I have been using the information here to get my water sparkling clear (thanks!). Will need to replace my filter and will replumb all above ground pipes this spring. I currently have a 1.5 hp pump and a 60 sq ft de filter, but am wondering if that is too much for my setup. Here is my pool information:
40x20 rectangular with diving board deep end, estimated at 33000 gallons.
I have 3 skimmers, going through two 1.5" pvc pipes to 2 shut off valves, then combining into one 1.5" pipe going into my pump
1.5 hp hayward super pump, going through 1.5" pipe to 6-way valve and 60 sq ft de filter
1.5" pipe to heater to a single 1.5" return pipe with 3 returns in pool
bottom drain disabled

I have an opportunity to buy a 48 sq ft filter with 1 hp pump. My questions:
is 48 sq ft sufficient for my size pool or should I just look for another 60 sq ft?
if 48 sq ft is ok, do I continue to use my 1.5 hp pump or would 1 hp be better?

Thanks!

 

[thepoolman]

You have a pretty large pool, so sticking with the 60 may be a better option.

Does the pool get a lot of debris? The difference between the two is going to boil down to having to backwash/clean the 48 more often than the 60.

If it were me and the 60SF filter were in good shape, I would ditch the multiport valve and install a push/pull valve in it's place. All the water that runs through multiport valve has to go through a hole about the size of a couple quarters. With the rest of your money, get a 2 speed pump setup.

 

[pooldv]

+1 on getting a 2 speed pump to save a lot of money on electricity. 1hp or 1-1/2hp will be plenty. With filters bigger is better because you have to clean them less often. Were you happy with the cleaning schedule for your current filter?

 

[jcverheijen]

Thanks for the replies. If I were to buy brand new I would stick with 60 sq ft. When my pool chemistry is ok I only need to backwash every 2 months or less. I found a used good condition 48 sq ft filter for much less than a new 60 sq ft filter, so am tempted to do that and live with slightly more frequent backwashes.
I have no plans to replace my pump anytime soon, it works great and was overhauled 2 years ago. The used filter would come with a 1 hp pump and I was wondering if my 1.5 hp would be too much for the 48 sq ft filter to handle.
When I do the math, I think 1.5 hp is fine, not knowing how many ft of head I have I assume the pump puts out between 40-70 gpm. I run the pump 12h per day, which is about 1 turnover?

If the only difference between 48 and 60 sq ft is the frequency of backwashes, I think I will go with the cheap 48 with my original pump. Is there anything other than frequency of filter maintenance I am missing?

What would be the advantage of the 2 speed pump? I still would have to run it for 12h per day on high speed to achieve a turnover, right?

- - - Updated - - -

Oh, I forgot to mention: my current 60 sq ft filter is in need of replacement. It has a pinhole in the housing, the clamps are broken, the unions are seized/dried out and the valve is leaking. I think it is original to the pool (30 years old......)

 

[cowboycasey]

we recommend starting at 4 hours of pump time depending on what type of pump you have... also, most go with the biggest filter to save water and frequency of backwashes. But it is up to you

Pool School - Determine Pump Run Time

A 2 speed may save you money depending on how much you run it on low and your price for electricity, it has saved me so much money

 

[pooldv]

The 48sf filter can handle either pump fine and the only downside would be more cleaning. So go for it. There is likely no need to run 12 hours and turnovers are not a meaningful measurement in residential pools. As Casey suggested start with 3 or 4 hours and see if your pool stays clean then you are good to go. Maybe split it into half in the morning and half in the afternoon for skimming purposes. As for a 2 speed pump, you would be able to run it on low for filtering. On low speed a 2 speed pump moves half the water but only uses 25% of the electricity used on high speed.

 

[jcverheijen]

OK, thanks that makes sense. I think I will buy the 48 sf filter and stick with my current pump for now, but will go down to 4h of pumping/day. That should cut the electricity bill significantly. If/when my pump needs replacement, I will look into the dual speed pumps, that makes a lot of sense now. If I find that the backwashing of the 48sf filter becomes too tedious, I can always go up to 60 sf at that time. This just seems like a really good deal, so well worth a shot!

 

[pooldv]

I agree, good plan!