I have 2 MJ1200's and a Seio 620 in my tank. That combined with my main return I push about 1800 gph in my 75 gal. The swirl attachment you have on the back PH will reduce the flow from that one.
I have considered setting up a closed loop in my tank but a Seio 1500 might do the trick as well. I have SPS so flow is what I want.
Make sure you are testing your source water for PO4. I assume you are using RO/ DI water? RO water won't always be enough. How old is your tank? The pic does not look too bad really.
HTH
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*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,
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