The filter pressure gauge is reading 22 PSI (recently backwashed).

Using the calculations from a post by mas985 I ended up with:

Return Dynamic Head = 2.31 * 22 (Filter PSI) + 3 = 53.82

Suction Dynamic Head = 1.13 * 6.5 (Inches Mercury) = 7.345

Total Dynamic Head = 53.82 + 7.345 = 61.165

Based on the curve for the WFE-6 pump it looks like GPM would be about 95 GPM:

My IG pool is freeform and is about 20K gallons with two skimmers and one bottom drain with 1.5” piping. From what I have read the plumbing flow rate would be 3 * 42 GPM (each 1.5” pipe max flow rate) = 126GPM.

The filter is a FNS DE 60, which has a max flow rate of 120GPM. Taking the lesser of the pipe and filter flow rate, it seems the 95GPM the pump is supposedly pushing, I’m getting decent flow rate. But I would like to get more flow to my spa spillover and the bubbler on my tanning ledge (it’s just a return pointing upwards). I can’t seem to get good flow at both the spillover and the bubbler return at the same time.

I mentioned in a previous post that I am considering replacing the two skimmer baskets and piping and the two pool return runs with 2” pipe since I’ll have the pool deck torn up. Is this worth it and will I be able to get more flow for my waterfall or at least the reduced TDH from the 2” pipe may provide future flow rate if needed?

I’m thinking reducing the TDH with larger pipe will allow more flow rate. Is this right?