Calculating head and proper filter pressure

[mas985]

Ok, based upon that information here are a few estimates and I say estimates because we really don't know what is happening on the suction side but from the filter pressure I can get close. We can nail it spot on if you can actually measure the suction at the pump via the drain plug but you would need a vacuum guage for that.

Anyway, here is what I have:

With the single 1 1/2" line: ~40 GPM @ 50' of head
All lines open: ~48 gpm @ 44' of head

The filter can probably handle much more than that so I wouldn't worry too much about flow rates.

Let me know if you need anything else.

[Water_man]

Thank you, Mark, for the calculations.
Without a flowmeter or a vacuum gauge I can't verify these numbers. However, the currents produced at the return outlets
indicate a strong flow. Can one have a "feel" for the flow rate from the intenisty of these currents? I can post a pic if this can help.

Suppose I want to get a vacuum gauge, I have two questions:
1. Where can you get it, and would it fit the hole in the skimmer?
2. Is there a way to comensate for the suction pressure drop between the skimmer and the pump? I undewrstand that what you need is the actual pump suction vacuum.

[mas985]

Thank you, Mark, for the calculations.
Without a flowmeter or a vacuum gauge I can't verify these numbers. However, the currents produced at the return outlets
indicate a strong flow. Can one have a "feel" for the flow rate from the intenisty of these currents? I can post a pic if this can help.

Suppose I want to get a vacuum gauge, I have two questions:
1. Where can you get it, and would it fit the hole in the skimmer?
2. Is there a way to comensate for the suction pressure drop between the skimmer and the pump? I undewrstand that what you need is the actual pump suction vacuum.

I think it would be really hard to judge flow rates by feel.

Any auto store or Sears would have vacuum guages for autos which work fine for this application. They come with tubes and if you get the correct adapter, will connect to the pump drain plug on the suction side which is the best place to connect it (no corrections needed). I think the adapter is 1/4" hose barb 1/4" male thread. Use teflon tape so that air does not leak into the pump.

However, the flow rate approximations are good enough for turnover calcs and filter limits. The error is probably less than 10% for flow rate. The vacuum measurement will get you that last 10% but at some cost and trouble.

[Water_man]

The drain plug! of course. Silly of me - I didn't see it.
Off to Sears tomorrow to get a vac gauge. Hopefully unscrewing the plug wouldn't be a big deal.

[Water_man]

Ok, based upon that information here are a few estimates and I say estimates because we really don't know what is happening on the suction side but from the filter pressure I can get close. We can nail it spot on if you can actually measure the suction at the pump via the drain plug but you would need a vacuum guage for that.

Anyway, here is what I have:

With the single 1 1/2" line: ~40 GPM @ 50' of head
All lines open: ~48 gpm @ 44' of head

The filter can probably handle much more than that so I wouldn't worry too much about flow rates.

Let me know if you need anything else.

OK, I finally got my vacuum gauge from amazon on line (Sears and others don't carry it) and I also replaced my
older filter pressure gauge.
The filter pressure when all returns are open is 11 (old reading was 9) and the pump vaccum is 14 inch Hg, which means head of 41. You came up with 44. Good job, thanks!