Will this work? (some idea's river manifold)

[Godfather]

I'm considering buying a rather unusual sized tank: 90cm x 60 x ?? (length x widh x height). Now I was wondering: because of the widh I think it's best to use 3 powerheads. I'm thinking of 2x Aquaclear 30-301 (540 litres p/hour with venturi) and 1x Aquaclear 50-402 (946 litres p/hour with venturi). Because I want to create a river, I want to fill the tank with only about 17 cm of water.

Do you think these 3 pumps together do have enough capacity using the river manifold idea or are they too strong and create backflow in this tank?

I want to create a riverbed and at the front window of the tank the depth will be 17 cm. At the back of the tank, the depth will be minimalized, so I was thinking putting the stronger pump at the front window.

What do you think of this idea?

[Diana]

I think better in American units... lets see...

90 x 60 x 17 cm = 92 liters, or around 24 (American) gallons.
(36" x 24" x 7")
You want to add PHs with about 2000 lph of flow (Skip the venturi- no need to waste power adding bubbles- there will be more flow if you do not use the venturi feature, better use of electricity) This is a little over 500 gallons per hour.


SO...
you are thinking about 20 times the tank volume in movement per hour. This is great.

You want to spread out the PH so that (Hopefully) there is less swirling. Hmm...

I think I would try to make a larger intake, rather than the point intake of the original river tank manifold. Have a look through the DIY projects, and see if there is a design for setting a sponge (pretty coarse) across one end of the tank and hiding the intake pipes between the sponge and the end wall of the tank. Another option might be a larger sponge over a pipe with lots of holes. The water will flow through the sponge more freely, perhaps resulting in less swirling around elsewhere in the tank.

I would see a problem in the shallow water. Would the fixtures fit? Far enough under the water that they will work silently? My Aquaclears do not like to have even the top of the PH out of water, and anything more than about 1/2" (1 cm) they make way too much noise. I keep mine under at least an inch of water, so that as the water evaporates (Very warm, dry weather here in sunny California) the pumps are not exposed.

I have a similar (smaller) tank:
30" long (75 cm) x 12" (30 cm) and 12" deep (30 cm)
This is a 20 gallon long tank. I have a canister filter with the intake at the west end of the tank, and the outlet at the east, rear corner, at the top of the water level. There is also a smaller powerhead with the sponge intake at the west end, and the PH at the east end, pretty low in the tank.
There is a lot of swirling of the very top of the water, but I can follow fish food that drops through the water. Below that upper inch or less (2.5 cm) of swirling water the flow is more like a river, east to west.
I might get it a bit better by moving the outlet from the canister filter to the east end, instead of high up at the back corner. Hard to modify this filter outlet, though.

I think you are on the right track to get several power heads and spread them out like that. In other, larger, tanks I have more than one power head, and having several outlets for the water makes the water flow more smooth.
Another tank:
4' x 16" x 16", about 45 gallons.
1.3m x 40cm x 40 cm, about 200 gallons.
The filter is a hang on back, but I have added a manifold to the intake so it gets all its water from the south end of the tank, and it is on the back, but as far north as I can put it. Water still is aimed at the front of the tank.
2 power heads, an Aquaclear 110 and a Koralia 4. The Aquaclear has a sponge intake at the far end of the tank. The Koralia takes its water from right there where it is, no modifications.
This tank has less swirling than the 20 long described above, in spite of what sounds like a mixed up flow. I see very little swirling at the top (Duck weed) and food follows the flow of the Koralia and the Aquaclear power heads, shooting toward the far end of the tank.

[Godfather]

Thank you so much for the reply! It made me think and I decided to get a far much bigger tank than I wanted before. Because in a bigger tank it's easier to handle the backflow I think. I have some idea's yet but I really want to think it over before I start with a new tank.

Plans are now:
Size of the tank: 140 cm x 65 cm x 40 cm (55inch x 25inch x 15 inch)
3 pumps (3x 802)

The problem with the river manifold is that the pumps are highly visible. I'm thinking of a way to solve that problem. Does anyone have some idea's about that?

By the way, this is the current set-up (small aquarium of about 80 litres) and Tunze nanostream pump, 2500 litres p/hour).

[Diana]

I have 2 ideas about hiding the pumps inside the tank.
1) Start with a longer tank. Use a pile of rocks to hide the equipment at both ends. Somehow make sure the sponges are not being compressed and are easily accessed for cleaning.
2) Start with a longer tank. Use some sponge material that is like a large sheet over one end, and put the intake tubes behind the sponge. Camouflage the the sponge by cutting some lumps that make it look like rocks. As it picks up some debris, algae and bacterial growth it will look less conspicuous. If you start with a black or dark sponge that is already a sort of natural color it will probably look better faster.
Make a similar sort of thing for the end with the powerheads, but cut it out of Styrofoam and coat it with Sika Top, potable water material. This is a concrete product. You can color it with any of the concrete coloring materials. Davis, Tru-Tone, Brickform and others. (These are all USA products. Similar products are probably available in Europe, but I do not know about elsewhere)

Another concept:
No power heads inside the tank.
Use a big enough canister filter to give you the water flow you want, and make a manifold sort of intake and outlet that you will then hide behind rocks or Styrofoam.
Perhaps a couple of spraybars at the north end, one set high and the other set low as outlets, and 4 of them used as intakes at the south end. Probably cut more or larger holes in the intake spray bars.