flow for closed loop

The Grizz · #1 02-23-2012, 11:23 PM

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

randy123 · #2 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 · #3 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 · #4 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 · #5 02-24-2012, 12:06 AM

80 % closed loop circ

sphelps · #6 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 · #7 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.

whatcaneyedo · #8 02-24-2012, 02:25 AM

I love my OM 4 Way which is fed from a Reeflo Dart on my 120gal. 2" into the pump, 1-1/2" out into the 4 Way and then four 1" returns. Its been running problem free and dead silent for several years. The back pressure/ head loss of it is no different than that of a T fitting.

I don't like the idea of having large aquarium pumps or even cheep power heads switching on and off constantly. I know Danner Mag Drives handle this poorly as I've wreaked a number of impellers this way. I've wreaked quite a few maxi jet impellers by switching them on and off too. Perhaps the higher quality pumps would handle it better but I'd do some more research.

I've always personally believed that LPS should have no less than 20x turnover. There are at least a dozen different LPS with 30x to 60x turnover around them in my system and they all appear to be doing great. Except for those that were preyed upon by my fish... There are plenty of pictures for proof in my Tank Journal.

Obviously I'm also very pro closed loop. Big ugly power heads stuck to the glass ruin a display in my opinion. Especially when they become plugged up with algae and debris. Yes the electricity consumption of a big pump sucks but I feel that its worth it.