New to drilled tanks...

AllSignsPointToFish · Oct 5, 2015

My first go-round with reef tanks ended about 10 years ago. I had a 90 gallon acrylic tank with an internal filter/overflow arrangement (i.e., not drilled and no sump).

Fast forward to today, and I'm starting a 135 gallon glass tank that is drilled. Even though I've done this before, the technology has changed a lot in 10 years, and now I have some newb questions. I've tried to find the answers myself, but that can be difficult if you can't adequately describe the situation in words or if you have no idea what the correct name of the device/feature is. So, I'll just let them go and watch the fur fly

The overflows in this tank have a what appears to be a double wall. This can't possibly be for filter pad, can it? I mean, how is one supposed to insert filter media in this space, not to mention how ineffective this filtration would be.

Here's another shot, slightly different angle.

There are also several sections of slits akin to the overflow weirs yet farther down the overflow box, but I can't figure out how these are supposed to be useful as well. As far as I can tell, the inner wall extends completely down to the floor of the aquarium, as expected, so that the tank will not completely drain in the event of a plumbing break.

Thanks again for the patience and my apologies in advance for the newb questions.

TreyC2010 · Oct 5, 2015

It may be that the slits down low flow upward through the double wall to give a little more circulation. That's what I see when I look at that. It's definitely not for filter media as that's why they make the sump. I'm almost positive it's for sucking in water mid and low in the tank

AllSignsPointToFish · Oct 5, 2015

That could be. Unless the top weir overflow generates some sort of venturi-type action, though, it seems like there wouldn't be enough driving force to generate any significant flow??

TreyC2010 · Oct 5, 2015

ImageUploadedByREEF2REEF1444092951.869045.jpg

I found this picture example online.

Fin · Oct 5, 2015

It's a MegaFlow overflow. It is simply drawing water from different levels of the tank. The top part skims the surface and the lower slots draw water from the lower levels and it mixes together as it goes over the top of the inside weir and down the drain to the sump.

AllSignsPointToFish · Oct 5, 2015

That's really cool. Thanks, all.

Trey, your diagram also unwittingly answered my next set of dumb questions

AllSignsPointToFish · Oct 5, 2015

I have looked and looked, but I can't find the manufacturer of this tank (I got it for free). Is there anyway to confirm the make of an all-glass aquarium if there are no stickers on it?

TreyC2010 · Oct 5, 2015

Put a full tank shot and we'll look too.

AllSignsPointToFish · Oct 5, 2015

They're not great pictures (and pardon the cats), but this is what I have convenient:

TreyC2010 · Oct 5, 2015

Also, I have one great piece of information on filling up the sump and tank with water. 1. Fill up the tank to where it overflows into the sump. Don't fill the sump completely. Just halfway 2. Cause a "fake system failure" by unplugging the skimmer, return pump, or anything that holds water. Allow it all to drain and settle 3. Fill up the remaining space in the sump to as far up as you feel comfortable. (I did 1" from the top of sump) 4. Plug it all back in and mark the top of the water line in your sump. This will be the maximum fill line when you top off or add water.

It seems complicated but take that step by step and you'll understand as you see it happen.

TreyC2010 · Oct 5, 2015

Is there a sticker on the inside of the glass? Like a manufacturers date or something?

AllSignsPointToFish · Oct 5, 2015

Here are a couple of more, minus the cats

TreyC2010 · Oct 5, 2015

Up around the top rim.

AllSignsPointToFish · Oct 5, 2015

I like the sump fill procedure. I was thinking about doing something very similar

I guess great minds think alike.

No, there is no manufacturing date or stamp as far as I can tell.

TreyC2010 · Oct 5, 2015

http://www.aqueonproducts.com/products/predrilled-aquariums.htm
Look at the 125 and the overflow slits. Is that your tank? Also the measurements. If the measurements fit then you have a 125.

AllSignsPointToFish · Oct 5, 2015

Yeah, that must be it. I was looking at Oceanic and All Glass and other brands, but this is as close as I've come. I thought it was a 135Gallon tank, but maybe it's actually a 125G.

TreyC2010 · Oct 5, 2015

Those overflows look so similar to the pictures so that's what got me. I had a 150 deep tank and I loved it. You'll love this big guy once you get it running.

AllSignsPointToFish · Oct 5, 2015

It looks like a pretty nice tank. Unfortunately, I have more dumb questions.

Is there a way to calculate the weir overflow rate? I have 16.5 inches of overflow weir. I think I need to make sure the circulation pump has a capacity not to exceed the weir overflow capacity. My quick calculations show an overflow rate of 1100 gpm. Does that sound anywhere near accurate?

Also, once the pump discharge lines are routed back through the overflow, it looks like there are two knockouts on the sides of each overflow box. Is there any guidance on how to direct the return flow into the tank for optimal circulation?

TreyC2010 · Oct 5, 2015

Honestly I can't give exact info on the overflow rate. I don't think you'll exceed those two overflows with 1100 gph but look at similiar tanks on here and see what they use. Ask on the build threads and people will be glad to help.

As for flow, you'll tinker with it continually until you find what you like. Use loc line for a return nozzle. It's great. Or if you have some $ to spend then get a sea swirl. I have one and its amazing. It rotates my return back and forth.

TreyC2010 · Oct 5, 2015

And no question is a dumb question. Some people jump on here and know NOTHING. We like to answer dumb questions because we've all asked them at one time.