rectangular tanks with vortechs on back wall

[jacksonpt]

Anyone tried this?

I've got a pair of MP10s in my 30long that I keep pretty low for my LPS. Currently they are on either end/side as you would expect vortechs to be positioned. I'm thinking about trying them on the back wall to see if I get better flow through my rocks. I know I'll have to keep them set pretty low to avoid sandstorms, but I think it's worth trying.

Anyone done it on a standard rectangular tank?

 

[Jacwil]

I never ended up trying it but here's some info.

http://reefcentral.com/forums/showthread.php?t=1816885&highlight=mp10

 

[Conesus_Kid]

I've done it. I don't really like them hanging off the sides of the aquarium, but to be honest, they don't work nearly as well when mounted to the back wall in my experience.

 

[jacksonpt]

I'm going to try it... hopefully tonight. I've been really disappointed with them on the sides, so we'll see how they do on the back.

 

[Gary Majchrzak]

IMO/IME pushing water from the back wall to the front main viewing panel isn't a good idea unless it's done at the bottom of the aquarium.
Detritus accumulation at the back bottom corner of any reef aquarium should be avoided.

(This is why everybody used to run spray bars at the back bottom of their reef aquariums years ago.)

 

[Capt_Cully]

I'm gonna try it in my new tank, but again, it's an MP 40 in a 3 foot wide (front to back) tank. I'm planning on employing opposing flow with penductors closer to the surface. I'm not going to have the Vortech going at full bore initially. Going to try for a front to back gyre. Not sure it can be done with the aquascape I'll be constructing.

If it was 2 feet front to back, not sure I'd try it at all. Just gotta experiment, see if you like it.

 

[jacksonpt]

IMO/IME pushing water from the back wall to the front main viewing panel isn't a good idea unless it's done at the bottom of the aquarium.
Detritus accumulation at the back bottom corner of any reef aquarium should be avoided.

If I'm reading into this correctly, why does front-to-back flow make deterius accumulation worse than side-to-side flow?

 

[Capt_Cully]

My guess is, historically it's harder to get to, and after a while it can significantly build up and start to leach nitrogenous waste back into the water collumn. Just a stab at what Gary might be talking about.

 

[jacksonpt]

My guess is, historically it's harder to get to, and after a while it can significantly build up and start to leach nitrogenous waste back into the water collumn. Just a stab at what Gary might be talking about.

What's harder to get to? I understand the effects of detrius accumulation, but what I took away from Gary's post was that front-to-back flow leads to more/faster accumulation than does side-to-side flow, but I don't understand why.

 

[Capt_Cully]

I was thinking he meant that siphoning off detritus against the back wall of an aquarium, behind the aquascape, might prove more cumbersome. Therefore, it might get overlooked and it might build up rather quickly.

As it pertains to hydrodynamics of a longer run (lengthwise) versus a front to back "barrel roll" gyre, not sure what he was getting at. That's just what I was thinking.

If you're refering to one Vortech, I could see how the wider surface area you'd be pushing away from (back wall of aquarium), would leave dead spots, I don't think 2 (like you're running) would, at least not as much. I'd be interested in hearing from Gary to see if he's refering to something more simplistic, like I was thinking, or if it is indeed more complex.

 

[d0ughb0y]

IMO/IME pushing water from the back wall to the front main viewing panel isn't a good idea unless it's done at the bottom of the aquarium.
Detritus accumulation at the back bottom corner of any reef aquarium should be avoided.

(This is why everybody used to run spray bars at the back bottom of their reef aquariums years ago.)

this is interesting. I have my powerheads slightly above middle and I notice detritus always end up at the back. I will try to move the powerheads to the bottom and see what happens. sinking pellets tend to stay at the bottom and at least if it is in front, the fish will see and eat it, whereas I see it get buried in the sand at the back.

 

[Tonynlo]

I use 2 MP40's in a 48" 90 gallon tank, placed about 3/5ths of the way up the wall at about 60% speed. I've tried them on the back and cannot get a consistent "random flow", if that makes sense. With the 1 pump on each side, I run them on short pulse anti sync and have a very controlled, yet irregular flow throughout my tank. With 2 MP10's in a 36" tank, you shouldn't have a problem creating flow from the sides if you just play with the configuation a bit.

The spread of a vortech is what is most appealing to me and having them on the back of a tank limits the amout of area it covers before the water is pushed into the glass and dispersed.

 

[Gary Majchrzak]

every aquarium is different but one of the most common problems encountered is accumulation of detritus along the back bottom of a reef aquarium behind/beneath the rock stack.

When I started experimentation with water movement in a rectangular shaped reef aquarium the "magic" happened when driving water flow parallel along the length of the aquarium. Best results happen with at least 3 powerheads: two that moved water in opposite directions (circular) alternately (reversing the main gyre) and at least one other that ran opposite the prevailing gyre intermittently. This last powerhead running intermittently against the main gyre along the back usually does a good job at getting detritus up into suspension but IME all reef aquariums need to get 'stormed' with a powerhead every now and then in order to kick up crap that sits stagnant in dead zones.