flow for closed loop

randy123 · #1 02-23-2012, 10:51 PM

Wondering if anyone knows the recommended flow rate for a predominately LPS tank. I'm looking at installing a closed loop, and need to decided which direction to go.

Reef Pilot · #2 02-23-2012, 11:05 PM

Why would you go with a closed loop system instead of in-tank powerheads or a WaveMaker?

I have a big honkin MDM pump with a 1/4 hp Baldor motor (thinking of selling it to someone needing a large return pump) that puts out 3600 gph (might be more) through 3 outlets in my 100g display tank, but barely moved stuff in my tank. I replaced it with a Coralife 5800 Wavemaker that produces a way more flow (no comparison, actually), and uses a fraction of the power. And no plumbing to set up. Also, you can adjust the flow to what is best for your corals.

sphelps · #3 02-23-2012, 11:11 PM

10X turnover is enough for LPS only. You can do more but going over 20X may actually cause problems but it does really depend on tank size, layout and flow velocity.

The Grizz · #4 02-23-2012, 11:23 PM

I have 3600 GPH on my closed loop on the 165gal, 4 returns though an OM 4way.

randy123 · #5 02-23-2012, 11:28 PM

What types of problems with higher flow might you expect? I am planning on mainly lps, but I would like to leave the door open for a few easier to keep sps if i can.

I was considering a dart pump on an OM 4 way, tank not as big as Grizz's though, its about 130 gallons (5')

sphelps · #6 02-23-2012, 11:32 PM

Many LPS do better in lower flow, many if subjected to SPS type flow requirements won't open and expand fully and do poorly as a result. With a closed loop you can point flow upwards towards higher portions of the rock work that could contain SPS and LPS will do well below. Also keep in mind if your pump is rated at 3600 GPH and you run it through an OM and typical tight closed loop plumbing you'll probably see closer to 2000 GPH if that. Closed loops don't have static head but do typically have more restrictive plumbing, especially on the intake which has the greatest effect.

randy123 · #7 02-23-2012, 11:59 PM

I'm thinking of plumbing with spa flex after the OM, I think the discharge side with be completely free of 90s. I was thinking twin 1 1/2 inch lines going to a 2 inch header for the suction, one I can make straight down to the pump, the other will have a couple bends and a few foot horizontal run.

Do you know how much flow restriction occurs in the OM itself?

I like the idea of some slower spots for the lps at he bottom, as long as the gunk in the water will stay in suspension.

fencer · #8 02-24-2012, 12:06 AM

80 % closed loop circ

sphelps · #9 02-24-2012, 12:47 AM

For the intake you'll want dual 2" lines, not 1.5" if you're running a dart. Large strainers are key as that can be the biggest problem for restriction.

The amount the OM will restrict your flow will depend on the original flow rate but I find then pretty restrictive overall, I'm considering removing mine for this reason plus the timing motor tends to squeak, the drum jams up sometimes and it's a pain to maintain in tight spaces.

Personally if it were me I'd skip the OM and but two pumps instead. Plumb one pump to pull water from one side of the tank and push water in the other side. Plumb the second pump the same but opposite. Then use couple timers or a single timer and a NC+NO relay to switch between the pumps every hour or so. This way you get true alternate flow, less restriction and redundancy.

untamed · #10 02-24-2012, 02:00 AM

Each of my CL Dart pumps pull through a single 2" intake. Suction is not an issue. As said, the key is to have a large surface area strainer.

OM 4 ways work very reliably. I dislike the look of power heads in the tank.