Educate me a little on return pumps...

Technically, I think you could plug the holes in one of the overflows, but I don't think you would want to do that. If the tank has two overflows, then that is probably the optimal design.

Keep in mind that for every piece of plumbing you add you lose GPH. This is especially true with vertical runs and elbows. So with a 800GPH pump, you'll be lucky to get 400GPH in reality. And yes, your overflows will send back exactly the same amount that your return pump sends into the tank. I think you'd need a pretty powerful pump to max out the overflows on a 120.

Honestly, I use the cheap rio pumps and I have had no problem with them, but I know that some people have had issues with them. Eheim, Mag and Ocean Runner are all nice pumps. I'd avoid the "Quiet One" pumps because they tend to not restart after a power failure.

As far as heat goes, your pump will add some heat into the water, but probably a fraction of what your lights (or heaters) would.

-JB

 

You do not want to push your over flows to or even any where near capacity. When a snail, algae, dead fish ect ect blocks some of your flow you don’t want a over flow.
I have had just the opposite luck as JB, I have had at least 2 rio pumps die on me, but my quite one has been great. The rio pumps I had were bought 6 to 8 years ago though. I was thinking on my next set up I would use 2 small pumps on two different electrical circuits.

 

You bring up some really good points about the snails. That's definitely a good reason not to run them at capacity, but if your standpipes are well designed, it should really lower the chances of that happening. I'd be more worried about a snail covering the siphon-break hole in the return line.

That's a really great idea about the two returns. It's been in my plan for a while to replace my one big Rio return pump with 2 smaller ones. I didn't even think about running them on different circuits. That makes it even better.

gb: My Rio's are all the normal ones. The Rio Hyperflows are notoriously bad. I would avoid those if I were you.

-JB

 

I have had more rio 400 and 600 go out than I can count. I hate them. I would stick with the Mags or go with the ocean runner. I actually like the Genx as well although it i a cheaper pump. I have a Genx 6000 I just took off my skimmer if you are interested, about 4 months or less run on it. I can give you a good deal.

 

I use an external PanWorld 50px-x (1110 gph max but probably much less with my plumbing) on my 120 along with 4 mj1200's in my tank. I don't know how much heat would be added by putting the return pump in water, but for me I didn't take the chance as a chiller is not an option for me. I run this with 8 t5's above in a tiny room and have no heat issues.

 

I also have a an external Little Giant available ( I switched to a Dolphin) but it is a monster. You won't start having heat problems unless you have halides. That is what really heats up the water, the pumps will just make the problem worse.

 

Actually I would say for a 120 it is about perfect if you don't have much head height. It is 1500 GPH at 0 head height. Add about 5 foot of head and some bends and you will be about half of that.

Not pushing this pump, but I wouldn't not choose it because you think it is too much pump. I would be more concerned it is not enough pump.
Also, I would hook up both returns. If your sump is going to undertank why not.

 

I have an AGA 120 with dual overflows and run two Rio 3500's. It's been working great for me so far. Temperature hasn't been an issue, but we'll see what happens this summer. I've only had my halides since November.

 

If you are worried about to much flow or pressure just add a small bypass line with a valve to regulate it! Just tap into your main return with a tee, and run the bypass line to your sump (to bleed off some flow and pressure).
AS far as heat goes, use a fan to blow air across the water, it not only helps to cool the tank but helps oxygenation. Have it turn on when your M/H turn on.

 

If you are worried about to much flow or pressure just add a small bypass line with a valve to regulate it! Just tap into your main return with a tee, and run the bypass line to your sump (to bleed off some flow and pressure).
AS far as heat goes, use a fan to blow air across the water, it not only helps to cool the tank but helps oxygenation. Have it turn on when your M/H turn on.
I agree with the bypass to recirculate, but I don't think that moving air will oxygenate the water more. I also wouldn't add a fan unless I had to. If you use a fan to evaporate water you will make you room more humid and need a dehumidifyer. I try to use a huge sump to disipate heat.
But since I don't even have an aquarium, you might want to take my opinions with a grain of salt. It's kinda like people with out kids giving parenting advice...........