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For those of you with Rimless tanks...

I wanted to resurrect this thread and add another issue that is bothering me about my rimless tank.

I am running two 1/2" sea swirls on a mag 950 for circulation in a 58G Illuminata tank. This pushes my flow up to about the maximum for this size of tank with a constant sandstorm. In my old tank, this setup worked great because when the sea swirl was pointed directly at the front glass, the trim would knock the flow back into the aquarium. Without a rim, any flow that is strong enough to climb near the top of the rim will cause puddles on the top of the rim and eventually drip down the sides.

Basically, a rimless tank has lower flow capability than a tank with trim, unless you want to clean up a mess all the time.
 
Does anyone on here (or anyone you know) run MP-40's w/ a rimless tank? Do you experience the same problem that anathema does?
 
I had a rimless 48x18x18 in the past with 2 vortechs. I didn't have a problem with that. I guess its dependent on how high you are running your water. If I had a rimless I would run my water line about 1.5" below the top of the tank.
 
I think the only bad thing is jumping fish for me. Sometimes I get a wandering nassarius snail on the ground but that's all.

I have two mp40's for years now.

My tank is an ELOS 120 (48x22x22).

I run my vortechs at full blast (3,000gph each). I also have two koralia 4's in there, and the return is just an eheim 1260.

I get some salt creep on the glass near where the flow hits the front glass, but that's it.

The only way to get the water to spill over is if you pulse the mp40's to get a big wave going. I've done it a few times just for fun, then quickly learned it's not fun having a ton of water on the ground. But the pulse wasn't limiting on flow. I had to turn down the flow and adjust the timing between pulses to get it to wave enough to splash.

So no problems with flow.
 
I think I was partly misunderstood, and both those comments back up what I said. Of course, you can tune your flow to not slosh over with whatever flow creation system you use. My point was that the lack of a rim becomes a limiting factor for flow in a particular setup. If you have a rim that knocks the water back into the tank, the tank has a higher capacity for flow.

Yes, you can dial back the flow so it doesn't slosh, but if you had the rim in place you could run more flow in the setup.
 
anathema said:
I think I was partly misunderstood, and both those comments back up what I said. Of course, you can tune your flow to not slosh over with whatever flow creation system you use. My point was that the lack of a rim becomes a limiting factor for flow in a particular setup. If you have a rim that knocks the water back into the tank, the tank has a higher capacity for flow.

Yes, you can dial back the flow so it doesn't slosh, but if you had the rim in place you could run more flow in the setup.
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No we got it. I can turn my flow all the way up without sloshing over the rim. I can probably add 4x the amount of flow without a problem.

I think the fact that your tank is not water tight is a limiting factor on flow.

I've never needed to dial back on flow before.
 
That is not what Art just said though Anathema. He said his MP40s are on full. He just couldn't allow the MP's to create large waves, which is a good thing in regards to rimless tanks.

He even has (4) extra pumps in that tank besides the (2) MP40s. I doubt he could get much more flow into that tank ;)
 
I never said I had to turn my mp40s down either. The problem lies in the water level height. Elos tanks are well thought out in the fact that the water level is about 1.5" off the top of the tank. It allows you to push flow in the tank without the water sloshing over the sides.
 
You guys are still agreeing with me but you think you aren't. :)

It's ok though, because it's my fault. :)

For my setup, using sea swirls, I have a limit on how much flow I can send through them before I A: push the sand around or B: push water up the glass and over the side. This second limit is significantly lower than if I had a rim on the tank.

I have never owned an MP(any#) because I had the sea swirls in storage and they work, but Art's statement that he had to avoid large waves still backs up what I said. If the tank he used had a rim, he could create larger waves and the rim would knock it back into the tank. Regardless of what kind of device you use, the limit for any one device pushing flow up the side of the tank is lower with a rimless tank.

I see in my original post that I was unclear on this, because when I said: "Basically, a rimless tank has lower flow capability than a tank with trim, unless you want to clean up a mess all the time." what I actually meant was: "Basically, a rimless tank has lower flow capability when using the same amount of current generation devices than a tank with trim, unless you want to clean up a mess all the time."

Yes, I could add and add expensive pumps to increase the flow in my setup. Then I would be out more money and have a bunch of ugly plastic limpets in my tank. (This is not a slam against the MP pumps, I think they are GREAT, and miles ahead of suction cupped powerheads) However, with a tank with trim, I was able to use 2 sea swirls on a mag9.5 turned up to 100% without slosh, and this was plenty of flow. In a rimless tank, this exact same setup is pushing water over the side, which means that to produce the same amount of flow that I did in a trimmed tank, I need to add more devices to avoid pushing water over the edge. The overall capacity for flow is not what I'm trying to discuss, though I see that is how it was understood. I'm sure we could get massive amounts of flow in a rimless tank, but I also think it would take more devices to do it, which could detract from the goal of a clean and attractive tank.

Hopefully that makes more sense.

Edit: For the sake of clarity in the discussion, I will comment that my water level is approximately 1" from the rim, and I don't feel that I can lower it much more without creating a significant amoount of noise due to the sea swirls being very close to the surface of the water. You can call that a limitation of sea swirls if you wish to spare the rimless tanks. :)
 
actually, to make bigger waves I had to decrease my flow.

decrease

lessen

my flow had to be less than what it is to make a big enough wave

higher flow doesn't equal bigger waves

I had to decrease my flow

I think we agree that the lip helps you. I think we disagree that the rimless tanks automatically mean you can't have a lot of flow. I think we agree that certain patterns of flow won't work on a rimless tank, BUT it does NOT limit the amount of flow you can have. Nor does it impede on the tank's health at all.

I think you're describing how your setup is superior in all ways because that's what you have. We get it =)
 
kinetic said:
I think you're describing how your setup is superior in all ways because that's what you have. We get it =)
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No, you don't.

For one, I never intended to give the impression that rimless tanks can't have a lot of flow. They can.

For two, the whole point of this thread as I understood it was to provide information to people who might be considering purchasing a rimless tank, and to those people I would say it this way: A rimless tank requires that more care be put into designing the systems for generating flow because it has no rim to knock excess flow back into the tank. If, like me, you had an old setup from an identical sized tank and plan to use it for your new rimless setup, it may not work as well on the new tank.

As far as my setup being better? Not sure what to say to that, except that if you bought me an MP40 for christmas you'd see it on my tank shortly after. I have no idea how having something in storage and being cheap equates to you feeling like I think I'm better than you but see a Dr. if that inferiority complex persists. It's not healthy.

I've said elsewhere my setup sucks so badly that I won't take pictures of it, so wherever you got the impression that I think it's awesome MUST be a misunderstanding. Part of the reason I'm not happy with my setup right now stems from me using old equipment from another setup that isn't adapting well to a rimless tank, and I thought my posting here could save some others the frustration. Instead it just leads to several people who aren't in that situation talking BS. Have fun with that.
 
i think we're all saying the same thing! we just wanted to make sure it wasn't misunderstood that rimless tanks can't take more flow.

every setup has different characteristics, I'm sure everyone appreciates the call to attention that you would think a rimless tank wouldn't be able to deflect water back in case the water did do that in someone's setup.

Let's move on!
 
But are people really using the rim to deflect excess flow back into that tank?
Meaning, the water normally sloshes up so high that it hits the bottom of the rim.
I cannot talk for others, but I don't. The rim ONLY gets wet when I clean and slosh around a bit.
So in my case, there would be no difference between rimless and rimmed regarding max flow.
Why does that sound naughty? :)

HINT : There is a fix for the sloshing when you clean problem.
Most tanks will siphon back water to the sump a fair bit when you stop the pumps. Until returns break surface level.
You could deliberately lower it a bit, then simply turn off pumps when cleaning.
Probably gives you a couple of extra inches.
 
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