Overflow flow?

[Zach.Attack6]

Putting in an overflow box from Glass-holes.com I have a 90gal tank 48 x 18 x 24 and want to know if I should go with 1 700gph box or 2 of them one on each side or one big 1500gph box in the middle, will that be to much flow?

[der_wille_zur_macht]

The rating on the overflow box is a maximum, the *actual* flow is determined by your return pump. So, if you got that 1500 gph box but used a pump that put out 700 gph, you'd have 700gph flow.

[Reefugee]

IMO - that's WAY TOO MUCH FLOW. A lot of water going through the the overflow will result in a loud waterfall sound. I have a 120G and I only have 600gph going through my overflow system. For flow inside the tank, I'd use powerheads or a closed loop system.

[Amp2020]

Might be more expensive to buy two overflow boxes but if one should fail the other will save you. I like the idea of having one on each side. Might give you better skimming that way. The more surface area you have along the skimmer's dam. The more surface water its skimming. If you want to maximize your skimming, have a coast to coast skimmer installed all along the back of your tank. I have also seen a skimmer made out of a PVC pipe that has a slot cut along the top and connected to a hole drilled into the back. Took very little room and looked good but you would need to drill your tank first.

[firemedic0135]

<a href=showthread.php?s=&postid=15182659#post15182659 target=_blank>Originally posted</a> by Reefugee
IMO - that's WAY TOO MUCH FLOW. A lot of water going through the the overflow will result in a loud waterfall sound. I have a 120G and I only have 600gph going through my overflow system. For flow inside the tank, I'd use powerheads or a closed loop system.

I respectfuly disagree. I have a 90g same footprint with the glass holes 1500 box and it is very quiet.Mine turns around 1200 gph and works flawlessly.One 700gph will not be enough and why have two 700 gph when you can have one 1500? Doesnt make sense to me either.The 1500 box is VERY slim and causes no shadows whatsoever in the tank. While the coast to coast is a good design it looks abit to obtrusive to me(my personal opinion have never seen one in a tank in person).I removed the baffle from my 1500 box cause my tank is "in wall" and noise is not a factor for me.

[therealfatman]

<a href=showthread.php?s=&postid=15182659#post15182659 target=_blank>Originally posted</a> by Reefugee
IMO - that's WAY TOO MUCH FLOW. A lot of water going through the the overflow will result in a loud waterfall sound. I have a 120G and I only have 600gph going through my overflow system. For flow inside the tank, I'd use powerheads or a closed loop system.

I vote for your reply!

If you are going to supply tank circulation efficiently and economically the best methods are by using power heads or closed loop(s). Draining water to a sump below your tank is the least efficient and least economica method of providing tank water movement/circulation. It very definitely cost more money to pump water up from the sump against staic head (height difference between pump discahrge and highest point in tand return lines) than to use power heads or a closed loop. There is really no benefit from running more water through a sump than is required by your skimmer is fed from the sump than that can't be more efficiently and economically provided by power heads or a closed loop. The vast majority of skimmers used nby most hobby aquarists with tanks of 120 gallons and below have a flow thru capacity recommendation for only 200 to 250 gph.

[Zach.Attack6]

Thanks for all the great replies.. keep them comin

[Zach.Attack6]

I've been reading the "Fail safe overflow system" by Beananimal in DIY form and His system is good but seems to complicated for me. I wanted to know can the glass-holes.com one ever FAIL???
Has anyone every had it fail??

[firemedic0135]

<a href=showthread.php?s=&postid=15183091#post15183091 target=_blank>Originally posted</a> by therealfatman
I vote for your reply!

If you are going to supply tank circulation efficiently and economically the best methods are by using power heads or closed loop(s). Draining water to a sump below your tank is the least efficient and least economica method of providing tank water movement/circulation. It very definitely cost more money to pump water up from the sump against staic head (height difference between pump discahrge and highest point in tand return lines) than to use power heads or a closed loop. There is really no benefit from running more water through a sump than is required by your skimmer is fed from the sump than that can't be more efficiently and economically provided by power heads or a closed loop. The vast majority of skimmers used nby most hobby aquarists with tanks of 120 gallons and below have a flow thru capacity recommendation for only 200 to 250 gph.

Well if that is the case then I am fine cause I run a mag 9.5 on my skimmer and also run a fuge off the overflow. I also have a closed loop running 2500gph.I have tons of flow. I agree that you should get flow from a closed loop but if you can turn your tank over more often with a higher flow through the sump then why not? It does'nt matter if you run 3 times as much water throught the sump than your skimmer runs. It is still getting a fresh supply of water to skim.

[Zach.Attack6]

"An extreme example: Take two identical 40' wide ponds that are fed with the same amount of water, one with a 4' wide dam and the other with a 40' wide dam. It follows that for the same flow (lets say 100 gallons per minute) over the dam, that the narrow dam will have a very thick waterfall and the wide dam a very thin sheet of water cascading over it. Now place an oil slick over both ponds! It will take significantly longer for the 4' wide dam to clear the slick fro the pond. Why? Because much of the water flowing over the dam is from below the surface! Now apply this logic to your tank, but instead of an oil slick, understand that the surface of the water attracts organics from the tank. The logical conclusion? For any given flow rate, the wider the overflow, the better your skimmer and/or in sump filtration will work!" Quote by beanimal

Makes sence but
I dont get this
"The rating on the overflow box is a maximum, the *actual* flow is determined by your return pump. So, if you got that 1500 gph box but used a pump that put out 700 gph, you'd have 700gph flow." If this is the case why can't I use 1500gph box and just run my mag 9.5 for return, will this work?

[Amp2020]

<a href=showthread.php?s=&postid=15183178#post15183178 target=_blank>Originally posted</a> by Zach.Attack6
I've been reading the "Fail safe overflow system" by Beananimal in DIY form and His system is good but seems to complicated for me. I wanted to know can the glass-holes.com one ever FAIL???
Has anyone every had it fail??

Sorry I was thinking of a hang on external overflow box. The only way an internal overflow box like that could fail is if something completely blocked the outlet hole. Still possible but not likely.

[firemedic0135]

<a href=showthread.php?s=&postid=15183372#post15183372 target=_blank>Originally posted</a> by Zach.Attack6
"An extreme example: Take two identical 40' wide ponds that are fed with the same amount of water, one with a 4' wide dam and the other with a 40' wide dam. It follows that for the same flow (lets say 100 gallons per minute) over the dam, that the narrow dam will have a very thick waterfall and the wide dam a very thin sheet of water cascading over it. Now place an oil slick over both ponds! It will take significantly longer for the 4' wide dam to clear the slick fro the pond. Why? Because much of the water flowing over the dam is from below the surface! Now apply this logic to your tank, but instead of an oil slick, understand that the surface of the water attracts organics from the tank. The logical conclusion? For any given flow rate, the wider the overflow, the better your skimmer and/or in sump filtration will work!" Quote by beanimal


Makes sence but
I dont get this
"The rating on the overflow box is a maximum, the *actual* flow is determined by your return pump. So, if you got that 1500 gph box but used a pump that put out 700 gph, you'd have 700gph flow." If this is the case why can't I use 1500gph box and just run my mag 9.5 for return, will this work?

I see what your saying about the dam idea, but keep in ind that the surface of your aquarium is not a stagnant pond. I know mine is very turbulant. Why does it matter that the overflow box only takes the very top water. Why shouldnt it remove water from all areas of the aquarium. There are dissolved organics at all levels not just floating atop the water. Thats why turbulant flow is a good thing.It stirs the aquarium and keep particulate matter suspended so that it can be removed, and not settle down and decay.

And yes the overflow box will only flow as much water as you push through it. I use a 1500 gph pump on my return and after friction loss its around 1200 gph.

A mag 9.5 will only push 950gph at best so with a little friction loss you should have about 7-800 gph depending on your plumbing.

[therealfatman]

<a href=showthread.php?s=&postid=15183318#post15183318 target=_blank>Originally posted</a> by firemedic0135
Well if that is the case then I am fine cause I run a mag 9.5 on my skimmer and also run a fuge off the overflow. I also have a closed loop running 2500gph.I have tons of flow. I agree that you should get flow from a closed loop but if you can turn your tank over more often with a higher flow through the sump then why not? It does'nt matter if you run 3 times as much water throught the sump than your skimmer runs. It is still getting a fresh supply of water to skim.

Water drained to the sumps is a lot more expensive to return to the tank just for tank flow than providing that additional flow by additional closed loop flow or additional power head flow. As long as you are not diluting your skiimer chamber water by running excess water through the chamber then excess water flowing sump is just an inefficient way to provide additional flow within the display tank but it should cause no harm unless extreme.

If a person is feeding their skimmer by water from a skimmer compartment the discharge from the skimmer should not be back into the skimmer compartment but instead outside the compartment and the flow into the skimmer compartment should be just a slight bit more than the water flow thru the skimmer otherwise you the water being fed into the skimmer. If the skimmer is fed diluted water it will provide less net nutrient removal per pass than when it is fed raw water only.

[firemedic0135]

<a href=showthread.php?s=&postid=15183596#post15183596 target=_blank>Originally posted</a> by therealfatman
Water drained to the sumps is a lot more expensive to return to the tank just for tank flow than providing that additional flow by additional closed loop flow or additional power head flow. As long as you are not diluting your skiimer chamber water by running excess water through the chamber then excess water flowing sump is just an inefficient way to provide additional flow within the display tank but it should cause no harm unless extreme.
I am not debating the efficiancy of the return pump only that it doesnt matter how fast the water flows through the sump. IMO it matter not how much water you pass in front of the skimmer (as long it is at least equal to the rate of flow in the skimmer) it will function the same. fast or slow its still the same water with the same solutes.

[Zach.Attack6]

I think slower flow is better exspecially since I have a refugium, and I don't know if it effects the skimmer because in one case the slow flow, water in sump gets skimmed more but with the faster flow a greater amout of water gets skimmed, not sure

[firemedic0135]

I agree on the part of the fuge. My fuge and sump are seperate and on seperate feeds of the overflow. My fuge gets 1/4 of the flow.

[scaryperson27]

I never liked the above concept. I imagine water flow going through the tank and the sump to be somewhat relative to Wheel of Fortune. No matter how hard you spin that wheel, one of those little pizza slice sections of chance will spin the same amount of time clicking the clickr'.

In other words, if you have a faster water flow going through the sump, the water will spend the same amount of total time in the sump, over in a certain amount of time, the same as if the water flow were slower.

I do however like slower flow for other reasons though.
-Less salt creep
-less energy needs to be used to move the water
-filter socks don't overflow as easy
-the plumbing doesn't have to be able to handle Niagara Falls
-better for microbubble control

My boss has a 240 gallon mainly sps/lps reef with a rio 2500 for the return. The thing probably moves close to 450-550gph. The rest of the flow is done inside the tank.

overall, the concept of slow wins in my book because i don't understand of a good reason to have fast flow.

[therealfatman]

The problem with flowing a lot of excess water through the skimmer compartment lies in that with the increased flow and velocity of flow through the compartment you are also running an increased flow and flow velocity through the bubble baffles making them near useless as the bubbles stay in suspension in the middle of the stream of fast flowing, high velocity water. If you flow that excess water in to the sump past the skimmer compartment (into the return area) instead of into it then no harm is done. Then you only have the economic inefficiency to deal with. Supply more water to the skimmer compartment would not effect the skimmer. Discharging already skimmed water back into the skimmer compartment however does lower the nutrients removed per pass thru the skimmer as less nutrient concentray tion in mans less can be removed. I find discharging the shkimmer water staright into the bubble baffle area directly and excses overflow darin waterv directly into the return compartment works best. The refugium v can be either in between the baffles and the return compartment or at the other end of the sump and fed by its own valve adjustable drain line.

http://reefcentral.com/gallery/data/585/200287scan0003-med.jpg