Optimizing water flow in canister-filtered 36 gallon

[jayjay5531]

Hey folks!

I have inherited a 36 gallon bowfront with about 40-50 pounds of live rock (eyeball estimate). I got 5 blue-green chromis(es?) from a friend about a month ago and they seem to be in good health (there are no other fish/invertsnk in the ta). The filter is a canister filter by Penn Plax (Cascade 700, which is supposed to flow at 185 gallons per hour).

Currently, the filter intake is located at the back-bottom-right corner.
The return is located at the back-top-left corner.

Is this enough flow for the tank? Ultimately, if I wanted to get inverts/corals, what changes would I have to make?

Since both the intake and the return are towards the back part of the tank, does this just facilitate a current in the back section of the tank while creating a stagnant cesspool in the front of the tank?

The filter comes with two attachments for the return: the one that I'm currently using which dumps all of the water back out in one place (which is obviously more forceful), and alternatively you can attach a "spray bar", which gently returns the water through a dozen or so evenly-spaced-apart holes in a tube that horizontally extends the length of the back of the tank (the holes facing forward). Which of these is better? (Currently I'm using the first attachment, because I'm assuming that returning all the water in one place in the back-top-left corner of the tank encourages a stronger left-to-right water current.)

Should the filter return break the surface of the water or not?

Lastly, if I need to get powerheads (especially if I ever intend to get corals), where should these be placed strategically? Wouldn't putting a powerhead in between the filter intake and return interrupt the current and prevent the flow of water? What about for a HOB protein skimmer?

I guess this is a question about achieving steady directional flow (which my canister filter probably already does pretty well, from left to right) but also achieving random flow and avoiding any cesspools. Ultimately my question boils down to, how can I optimize water flow in this tank, especially if I want to get corals at some point?

Thanks!

 

[ReefsandGeeks]

I'd definently recommend at least 1 powerhead. I had a very similar setup before, with coral and got away with a single 800GPH cheap powerhead, but to get a better/more adjustable flow I'd recommend (2) smaller ones on opposite sides of the tank. The best way to "see" the flow in the tank is to put some crushed up flake food on the tank and watch how it moves around. Adjust the powerhead(s) while this is going on to try to avoid stagnant areas. once you get coral, this can be done to fine tune the local flow for whatever coral you have, as each coral likes different flow and light intensitys.

You may be okay without a powerhead for fish only, but would be very likely IMO to get stagnant areas which can cause detritus buildup and nutrient issues.

 

[ReefsandGeeks]

I had my powerhead on the left side of the tank, about 1/3 the way down, facing the front center of the tank. It provided enough flow, but there was some deadspots in the back of the tank, which is part of why I'd recoment 2 smaller powerheads. I know most people initially don't want to fill there tank with equipment and powerheads because it takes away from the look, but in a short time most of us don't even notice them. All I see in my tank is the rock, coral and fish. I don't notice the powerheads or return flows or heater or anything.

 

[jayjay5531]

Thanks so much for the responses! Given this information, I think I will buy two small power heads.

One follow-up question: Given that the canister filter is set-up such that the water flows from left to right, do you think I should orient the powerheads to push water from right to left in order to create more "random" motion (rather than one single left-to-right current).
(Either way I will make sure to orient them slightly forwards so that there is at least some flow at the front of the tank)
Thanks!

 

[ReefsandGeeks]

Nice! glad to help. If you're getting 2 powerheads, I'd probably put one on the right, and one on the left side of the tank. I currently have 2 powerheads on my tank, and a canister filter (65g tank). The way I have mine setup is I have the canister intake on the back right (canister intake really doesn't effect flow in the tank at all). I have the spray bar a few inches under water in the back center of the tank, facing slightly up to give a ripple in the very center of the tank water surface. If you have LED lights this will give a real nice shimmer effect. It also helps agitate the surface for more aeration. I have a powerhead on the left side, close to the surface and a bit closer to the back of the tank facing the right front of the tank, and another powerhead on the right side, about halfway down facing the front center of the tank. For me, this provides good turbulent flow as the flow from the powerheads collide a bit and cause some turbulent flow.

This would be a good start point, but you'll have to make adjustments depending on your rockwork. This setup might make a more stagnant area in the back behind the rock, so some adjustment may be needed. My tank is filled with different types of coral, so it's quite a lot of work trying to get them all to have the correct flow.

 

[jayjay5531]

I have the canister intake on the back right (canister intake really doesn't effect flow in the tank at all). I have the spray bar a few inches under water in the back center of the tank, facing slightly up to give a ripple in the very center of the tank water surface. If you have LED lights this will give a real nice shimmer effect. It also helps agitate the surface for more aeration. I have a powerhead on the left side, close to the surface and a bit closer to the back of the tank facing the right front of the tank, and another powerhead on the right side, about halfway down facing the front center of the tank.

Awesome! I'll start by trying to replicate this and make any adjustments if necessary