RTM - powerhead math (clarification)

[Holdstrong]

I just want to triple check my understanding and the math that goes into this before I spend money and build my manifold.

I have a new 75 gal tank.

I have read that you typically want about 12x turn over per hour. So that is 75 times 12 = 900 gph.

That would mean that two Aquaclear 70s (400 gph each) come close to this. With the filter output maybe providing the rest of the oomph.

On some level I am worried about over doing it. I envision me running the numbers wrong or understanding this concept poorly and blowing my fish up against one side of the tank. Ha!

Thanks for clarification.

[Martin Thoene]

If by RTM you mean River-Tank Manifold and you are intending it for Hillstream Loaches, then I generally factor in a minimum turnover of 16 X her hour as acceptable. Looking at GPH always seems excessive until you look at the turnover rate per hour.

You have to consider that in the wild these fish live in water that you might have trouble standing in it's flowing so fast.

If you're considering a River-Tank manifold for other types of loach then the turnover can be less, but you'll still want it to be high.

So what species do you intend to keep?

Martin.

[Holdstrong]

Yeah, I meant River Tank Manifold. Thought I was being cool by using the acronym.

The tank will primarily be the next step for our clowns, who have been doing their best to outgrow the 35 gallon tank we bought for them before finding this site.

I bought all of the pipe tonight for the manifold and look forward to assembling it. I have the extra filters ready to go (2 eheims), and we are changing to a sand substrate.

The only part of the setup I've had some doubts about was the powerhead strength and which to go with.

[Diana]

Have a look here also about the actual output of the Aquaclear brand of power head. Without some modification you will not even get the flow stated on the package. Modify them as shown, and I can tell the difference just by looking at them doing their job in my tanks.

The flow is also slowed as the sponges fill up. Keep them clean.

I usually keep regular community tanks with about 10x water flow from filter and power heads, but not uni-directional. My RTM is not quite at 20x, but it is close to unidirectional. There are some interesting currents in there.

[Martin Thoene]

Would this be the link you forgot to include Diana?

http://www.loaches.com/articles/water-m ... h-aquarium

Aquaclear powerheads rock IMO Holdstrong. I've used the old 802 models for years non-stop without any operational difficulties whatsoever.

Martin.

[Holdstrong]

Thanks for all the help.

I have to tell ya, playing around with this stuff today was so much fun. An absolute blast.

I am a butcher with a Dremel, but a little bit of persistence got the manifold together and the pumps modified.



And here it is fully stocked





I filled it up to just below half to test things out. Make sure there were no obvious leaks in the system etc. I have to admit I was just a little surprised when it all seemed to work.

I'm very impressed with those powerheads. They seem very strong for this size tank. I had a peace of driftwood in there not tied down and it was immediately pinned to the intake side of the tank.

My one concern was that there seemed to be an awful lot of back flow from the stream hitting the far wall and bouncing back out. I turned off one of the powerheads to compare the back flow but of course that only produce a circular flow.

A sponge dropped in the tank with just 1 powerhead active did perfect laps around the tank. With both powerheads active it shot to the back wall and would occasionally come a foot back out with the back flow and would dance around in some currents before being pushed back again.

Unless I am forgetting something obvious, my next step will be to position this tank where we want it and to begin adding the sand.

[plaalye]

is that a pic-tis cat? If so they grow very large and are notorious poop factories, you may be a bit overstocked

Have fun setting up your new tank!