Overflow box 1 or 2

[an411]

I have a 120 gallon tank with one overflow drilled would there be any reason or advantage of having the other side drilled and another overflow box installed or should 1 be fine.

 

[sir_dudeguy]

The hole that is already drilled....is it drilled in the center or the back corner? If its the center, i wouldnt drill it again. But if its the back corner, then maybe i'd do the other corner as well.

And i would definately do it if the tank was a longer one (i've seen 120's that are only 36-48 inches before...i wouldnt drill that in 2 spots, but the ones that are like 5-6 feet long...i definately would drill that in both corners. That way you get surface skimming at both ends of the tank.

 

[asm481]

Hold your horses here. The bottom might be, probably is, tempered. Most manufactured tanks with holes in the bottom are drilled then tempered at the manufacture. That means you will blow your tank up!

 

[an411]

Yeah I am not going to attempt to do it myself I am skilled but not that skilled it is in the back left corner and was done by the factory. Basically i was just wondering what are the advantages of having 2 overflows instead of 1.

 

[sir_dudeguy]

IMO your skimmer (if you have one) might do a little bit better. Because you'll have water going into the sump from 2 seperate places, meaning there's a higher chance that gunk will get to the skimmer (where if its just the one overflow, stuff might sit on the right side of the tank and never make it to the overflow on the left...but that could also be due to lack of good flow)

 

[an411]

Do you think that good water flow would eliminate me needing another overflow. I just see that most people that have my size tank have 2 overflows in each corner. I just don't want to regret not having it once the tank is all set up

 

[sir_dudeguy]

probably. What i'd do is make the flow mainly going that direction (towards your overflow) but dont get me wrong...have a few powerheads pointing in random directions as well.

 

[LooseHip]

one advantage of having two overflows is in the event that one plugs for some reason you will still have one that is functional. That way you do not burn up lets say a return pump.

 

[an411]

Yeah I was eventually going to look into investing in a few powerheads but that is after I set up my stand and Ro/Di system this weekend and figure out how to plumb the return and the overflow. Hopefully that wont be that difficult

 

[sir_dudeguy]

loosehip has a great point. I didnt even think of that.

But also, dont underestimate how much flow you really need. It seems like newbies especially do this. For a general reef tank, i'd start at at least 20 times turnover rate per hour.

so 120 (size of tank) times 20 is 2400 gallons per hour total. Thats after you add up all your pumps and return lines in the main display. Do not count skimmers into this tho.

I start with 25 times turnover per hour tho, but thats just me. If you're gonna do an SPS dominated tank, then you may wanna start with like 30 times turnover. It sounds like a whole lot, but its really not. I'd just stay away from powerheads like maxijets and stuff like that. They have a really narrow output that makes a violent jet of water. Feels like its pushing out a lot of water but its really not. You'd be better off getting stuff like seio's and tunzes which have a really wide output and make it feel pretty week, but they put out a lot of water which is what you want. You want the nice easy flow, not the very forcefull flow from other powerheads.

 

[an411]

I have a mag pump 2400gph I was thinking that it should be enough even though I know that you lose some of that with the plumbing

 

[sir_dudeguy]

I'd get more still. Like you say, you'll be losing some on the return, but you need more than one source of flow anyways (even if the return has a split or 2 in it...in a tank that big, its very easy to have dead spots).

I'd get at least 2-3 of the seio 620's or 820's. If you can afford a tunze, get those instead.

 

[an411]

now would you recommend those right away cause at first I plan on putting FOWLR

 

[an411]

Also for a tank that size what model tunze would you recommend I would rather get the best now and not have to get better ones later.

 

[sir_dudeguy]

If its gonna be a FOWLR for now, then i guess you got a little bit of leeway, but whenever you get the chance, add them. As for which one to get..i cant help you there as i've never used them (i've always had seio's). I hear that the tunze nano stream powerheads are crazy tho. I know they're really small and the output is at least 600 something i think.