Help with over-the-top return options?

[LeRenard]

I need some advice from someone who has done this before- I can't figure out my over-the-top return.

I've got a basement sump setup I'm working on. It's oversized for my current 36 bow front DT so I won't have to swap anything out when I eventually upgrade to a bigger DT (the goal is a 48" 120 or 150, probably in 10-12 months).

Right now it's an Eshopps RS-200 sump and I've got an Eshopps PF-800 HOB overflow (for various reasons I couldn't drill the tank, next one will be for sure). I've got a Jebao DC-12000 return pump so I can dial it back for the smaller DT and also to have enough flow to run my Carbon, GFO, and my small refugium from a manifold. I've got 8 ft of head going to the DT. Without the manifold the pump spec is ~1500 gph/6000 lph at 8 feet/2.5 meters. I'm only guessing but I suspect with friction loss, etc, I'll get ~500 gph/1800 lph at the DT. That gives me 13x turnover for a 36 gallon DT at full tilt or 4x for a 120 with some adjustability.

I've plumbed my return up to the tank with a 1" drain and a single 1.25"/32mm PVC return. There's two 90s (no choice), a union, an inline ball valve and a four T manifold off to the GFO, etc. The inline valve is to add back pressure if the head pressure isn't enough to divert enough flow to the reactors/fuge- I'm not sure if I need it.

The part I need help with is between that 1.5" PVC return and my tank water. I have to go over the top, but I can't figure out if I should just U the 1.25" in or split to two 3/4 or 1/2" returns? I'd like to use the pump to add some flow if I've got it to spare, and I was afraid just dumping it in will stir up the sand? Do I take the PVC below the water line or let it dump in with a 1" drop? I wouldn't get siphon that way but probably bubbles. There's room in the sump for some back flow when the pump is off though. Another option someone suggested at a LFS is to split the 1.25" with a SCWD and potentially remove my circulation pumps to safe the tank for a future anemone.

Short version- I've got a 1.25" PVC just under a 36 bow front with 0-~800ish gph (probably conservatively 500gph) of flow available (if I dialed back the manifold items I'm assuming I'd hit the overflow limi).. How would you get it in there?

It turns out almost no one ever shows this part of their plumbing in pictures.

[Gorgok]

I have 1.5" plumbing on that pump into my 75. It ends with a 90 to go over the trim, and a 45 to go into the water, with enough pipe after that to submerge the outlet a hair. Dumping all that water into the one spot did clear out the sand in that corner pretty good, but i put one of my powerheads in the way and its fixed. Still flowing 1500 gph without scouring out the sand.

[nemosworld]

It's pretty simple to me, bring the 1.5 inch pipe up to the back of the tank, then use a 90 degree elbow, get a bushing that will reduce it to 3/4 inch (Threaded) use a 3/4 inch loc-line.
you will have to clamp the pipe to the wall or your stand.

http://cdn.mscdirect.com/global/images/ProductImages/3699973-23.jpg

[dbl]

+1 with Felix above. I didn't have as much head loss, but I split mine, used the bushing shown above, and then 3/4" loc-line creating two returns. You can get various nozzles also to connect to the loc-line to vary the flow from the returns.

[Jim.mer]

I agree with the above poster but I'd like to add, Put a check Valve on your return, Don't use a SCWD, They get plugged up and look terrible in your tank.

[sleepydoc]

I just had a 45º elbow at the end of my return line. Loc line will let you direct the flow more, but it adds a lot of resistance and increases head loss.

Avoid check valves unless you absolutely have no choice. They are notorious for leaking in saltwater systems. Size your sump appropriately and allow some extra room in it, then either drill a siphon hole or place the outlet of your return close enough to the surface such that it breaks the siphon before enough water drains into the sump to flood.

[mighties_keeper]

Drop it over the trim with a u and make a T spray bar. Your sand will not kick up and lots of water flow distributed over a larger area.