Need a recommendation on Overflow...

twf0369 · Jun 20, 2018

My wife and I are putting an addition on the house and with that I will finally be getting a fish room. New fish room = New Tank.

My new tank dimensions are 96 x 30 x 25" and I need help picking an overflow size. As of now I am leaning towards the Modular Marine or Reef Synergy ghost overflow but need some guidance on what size to go with and how many. My plan is always SPS related so I know turnover is key.

Please let me know what you recommend.
Thanks in Advance.

hijinks7 · Jun 20, 2018

I'd go with two of the synergy 16 inch overflows. I have one on my 4 foot tank and works great.

Mark Bianco · Jun 20, 2018

First off congrats on the new tank and the new fish room it makes it soo much nicer to to work on. As for your statement “My plan is always SPS related so I know turnover is key.” I am going to have to disagree. Dont get me wrong flow is very important especially when growing SPS corals.

With out knowing what type of sump you intend to you use it would be almost impossible to correctly recommend overflow sizes. Please allow me to explain if you had a sump system that is only capable of handling 100 gallons an hour then recommending an overflow larger could be disastrous. Its all a matter of balance.

Lets take this further normally within a sump there is some type of mechanical filtering such as filter media or filter socks now if you run more water flow then the media is capable of handling then the rest will pass over the media not being filtered passing the dirty water to the next part of the sump.

From there most people run a skimmer if you have chunks of debris / unfiltered water passing into the skimmer section it will only cause problems and significantly decrease the skimmer effectiveness to do its job.

Some people then run a refugium the water need to move slow enough for the fuge to do its job.

Lets say you buy a big enough sump, filtration and skimmer to handle an impressive amount of flow however your bioload is small. Well when that happens your skimmer will dry cycle and you will get inconsistent of skimming some days it may be good some days nothing and some days overflowing.

IMHO For flow a set of good power heads do wonders when coupled with a properly sized overflow and sump system. As stated earlier a balance is what you want.

HTH

Mark

twf0369 · Jun 21, 2018

Mark Bianco said:
First off congrats on the new tank and the new fish room it makes it soo much nicer to to work on. As for your statement “My plan is always SPS related so I know turnover is key.” I am going to have to disagree. Dont get me wrong flow is very important especially when growing SPS corals.

With out knowing what type of sump you intend to you use it would be almost impossible to correctly recommend overflow sizes. Please allow me to explain if you had a sump system that is only capable of handling 100 gallons an hour then recommending an overflow larger could be disastrous. Its all a matter of balance.

Lets take this further normally within a sump there is some type of mechanical filtering such as filter media or filter socks now if you run more water flow then the media is capable of handling then the rest will pass over the media not being filtered passing the dirty water to the next part of the sump.

From there most people run a skimmer if you have chunks of debris / unfiltered water passing into the skimmer section it will only cause problems and significantly decrease the skimmer effectiveness to do its job.

Some people then run a refugium the water need to move slow enough for the fuge to do its job.

Lets say you buy a big enough sump, filtration and skimmer to handle an impressive amount of flow however your bioload is small. Well when that happens your skimmer will dry cycle and you will get inconsistent of skimming some days it may be good some days nothing and some days overflowing.

IMHO For flow a set of good power heads do wonders when coupled with a properly sized overflow and sump system. As stated earlier a balance is what you want.

HTH

Mark

Thanks for the post Mark. I guess I better select my sump, skimmer and return pump prior to making a decision on the overflows?

legionofdoon · Jun 22, 2018

I'm running a synergy 16 on a 40 breeder with a DCP 8000 running at 80% with no issues.

legionofdoon · Jun 22, 2018

Here is a pic before I stocked the refugium and I recently added a life reef skimmer.

ca1ore · Jun 22, 2018

I would ALWAYS suggest a single larger overflow than two smaller units. Simplifies plumbing and makes setting the drain flow much easier. In a tank of that size the internal skim box should be at least 36" to affect proper surface skimming. I'm using the MM 36" model on my 96" tank with about 1,300 gph and it skims just fine. Although SPS is generally demanding of flow, this is far better accomplished with in tank powerheads than from the main return pump.

I think the best approach is to select the overflow box that is going to give you acceptable surface skimming on an 8' 300 ish gallon tank, and then choose an approximate pump/flow rate which in turn informs sump size. Either way you're going to want a sump at least a quarter of display volume.

legionofdoon · Jun 22, 2018

I don't understand that power heads vs return. My return is a inch and a quarter and I have a ton of wide spread out flow. So far I don't know if I will need power heads yet.

Greybeard · Jun 22, 2018

Ok, so you're looking at a roughly 300 gallon display.

Most people these days shoot for 4 to 6 times tank volume per hour in sump turnover. If you're running Triton, they recommend 10x... so, at that level, you'll need 3000 gallons per hour. If you plumb for that level of flow, and decide to go with the more usual 1200 to 1800 gph turnover rates, no problem, you're just not going to push the overflow to it's max.

The 16" Shadow is rated for 1500 gph... seems a bit low for this. Does Synergy make a larger unit? I don't really know.

Modular marine does show one rated for 3000 gph. Nice looking, IMHO, though this is the first time I've ever looked at it. 30" long, 3 x 1.5" bulkheads... seems like it'd work with the dimensions you're giving just fine. Don't know how Modular Marine equipment does when you push it to full capacity... you might ask someone who has one.

I'm using kindof an oddball, the H2Overflow units from CustomAquariums.com. They're rated at 1200 gph, I've got two, should handle 2400 gph, and honestly, they're pretty much at full capacity if I turn my 1900 gph to it's max. I have very little head pressure, so it's probably running pretty close to listed capacity. In any case, I'm pretty sure the dual H2Overflows couldn't handle 2400 gph, even though they're rated for it.

Modular marine shows a single unit rated for 3600 GPH. I would probably go that route. It's not that much more than the 3000 gph unit, and having a little more overflow capacity than you're ever going to use is a good thing, really.

I'd probably couple the 3600 GPH Modular marine with a decent quality 3000 gph DC return pump, say, maybe a Vectra L1 or an eFlux 3170, so you can adjust flow, with the capacity to go faster than you're likely to want. Add in a good high flow sump, perhaps a Trigger Triton 44? and you're all set

legionofdoon · Jun 22, 2018

I've ran my DCP 8000 at 100% which is roughly 2000 gph at 0 head and I figure with my setup it's probably around 1600 gph and I still had to gate down my return so I'm sure the synergy is capable of doing more than 1500 however you will hear splashing from the weir. That's the only reason why I lowered mine to 80%