# Throwing some ideas around for a DIY 75G Acrylic Tank



## dam718 (Nov 25, 2013)

Hi guys,

Sometime in the future I'll be moving back to Georgia... I thought about just buying a 55G when I get there, and even considered having my parents buy one for me now that I can set up when I get there... But the more I think about it, I think I'd like something a bit bigger... 

So I've been toying with the idea of building a 75G acrylic tank, 48" L x18" W x 22" H.

Not sure exactly what kind of fish, but most likely African Cichlids, again... Cause I love them... Maybe even a Saltwater build... Will cross that bridge when I get to it... 

Anyway, I am thinking I want to do a sump system on this tank. And I wanted to talk overflows here... 

My idea, for now, is to do a coast to coast overflow on the back of the tank... Cut 1" deep combing across the entire back wall of the tank to act as my weir (The width of each cut, whatever the width of my saw blade is... 1/8" most likely). The overflow will be around 5" from the back of the tank with a depth of around 7" (this is what I calculate after cutting the panels out of a 4'x8' .5" Thick acrylic sheet). And for now I am considering using the Beananimal overflow design I found on a different forum. 

Something similar to what is seen here:










I want to have a flow rate of 700+ GPH, which this overflow design should certainly support. I have considered using 1" PVC for my drains... This should easily support 700GPH I am assuming?

Also, for a pump I was looking at a mag drive 12. I know it's rated for much more than 700 GPH, but I am taking head loss into consideration and want 700GPH minimum at a 5' head.

I wanted to use coast to coast for a couple of reasons... 

1) Maximize surface skimming
2) Increase the amount of time I have to react if something goes wrong.

I assume, possibly incorrectly, that if I have a large volume of space in my overflow area, I'll have more time to shut things down if it looks like the siphon isn't working right, or my emergency isn't supporting the flow rate.

And for now I am looking to do 2x 3/4" returns on either side of the aquarium, haven't thought much about placement yet. I have decided I like the idea of using check valves on the return as opposed to depending on having them high enough that they don't siphon more than a few inches of water back into the sump on a power failure. 

For bracing, I was looking to do 3" x 18" braces from front to back centered at 12", 24", and 36" as I just don't want to mess with euro-bracing... 

Obviously, the weir teeth would be cut around the areas where I plan to have the bracing welded in place.

This is more intended to be an open discussion on the design, and possible challenges I may face... I'm looking for any and all opinions to guide me in the right direction... Either good or bad, I am here to learn.

This will be a big undertaking for me, as I have never built anything like this before, and I want to get it right the first time around!


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## coralbandit (Jul 29, 2012)

Great idea and plan!
I would use a different pump though.I own several mags from model 3 upto model 24,including the model 12.
They are a little loud,transfer heat(can raise tank 4 degrees aprox),and use a good amount of electricity.
I would go DC.I recently replaced one of my mags(the model 24) with jeboa 12,000.
If your pump will be submersed then these are great pumps.
The model 6,000(LPH) would easily replace the mag 12 for the same price,save you electrcity,no heat transfer and are silent.On top of that they have digitally controlled speed settings(6) so there is no need for a ball valve to control flow.
jebao pump parts - BuyCheapr.com
They come in 6,000 ,9,000 ,12,000 LPH .


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## jrman83 (Jul 9, 2010)

I think an overflow that large would be unnecessary and may be more than you bargain for. Looks cool though. A 75g is just not that big to try and force that large of an amount of water out of it. What size sump do you think you will need to accommodate the flow in? You can effectively do the same thing with two corner overflow boxes. Or, why not get a SW designed tank with corner overflows and drilled?

Having the check valves on the pump is what I did and just safer. It is good to do but the same thing can effectively be done with a simple pin hole in nozzle of your return line that breaks the siphon. I had both. You will still get a few inches of water to flow back in through your overflow until the water level in the main tank drops below your overflows.


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## coralbandit (Jul 29, 2012)

I might be inclined to make my own filters,but I don't think I would try a tank.Especially anyhting over 50g.
I love my aqueon mega flows(pre drilled tanks).Anything under 120g mostly has only 1 overflow box(doesn't matter what brand tank),and then they get into 2 overflows for 120 and up.The general flow rating is 600-700 gph per overflow.
Head pressure and the use of elbows,along with the size of return lines is the largest killer of flow.I'm running a 3,000 gph pump on my 120g(from NJ) and the two overflows handle it well.It is less than 6' to top of tank and I run 1 1/2" until it splits into two 1" lines.I really thought I might have to dial this pump down,but it seems to be running fine.


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## dam718 (Nov 25, 2013)

I've worked with Acrylic before, although it was a far different application, same concept though... It's really super easy to work with, and I trust myself a lot more drilling and cutting up Acrylic than I do drilling and cutting glass

Not to mention, For the cost of a sheet of acrylic from a buddy in Atlanta, I can build an Acrylic tank for a fraction of the cost of other acrylic 75G, and around the same price as a mega flow glass tank. I'm a big fan of saving money!  My other concern, specifically with the Aqueon tanks was on the 75G there is only a single drain and single return drilled. I don't know how likely it is that the drain will ever get clogged, but I can certainly see how it would be extremely bad if it did. 

And that's why I wanted a very "safe" overflow design. It may be a bit overboard, but I really need to keep the water in the tank/sump, and NOT on my floor  The wife would never let me keep a tank again if I put even a drop of water on the floor!


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## dam718 (Nov 25, 2013)

To address the overflow size and amount of water it can handle... TBH, I have no idea how to calculate the amount of water my coast to coast design can support.

I only assume it is more than 700GPH (much more!)

Now, regardless of the amount of water a particular overflow design can handle, I thought the actual flow rate going in and out of that overflow was strictly based on the pump used. Because I can throttle the drain standpipes with gate/ball valves, I wasn't too concerned with their max flow rate, so long as it greatly exceeded what I THINK I need. If it turns out I need MORE flow later on, I can always accomplish that by turning up the pump flow rate and opening my drains up a little more... 

Big thing was safety... No water on the floor = happy wife = happy life... 

Now, as far as sump size goes... I haven't thought much about that yet...

Now is as good a time as ever... I don't plan for the intakes to be any lower than 3" below the water line, so if I add that much to my safety factor I want at least 10 gallons of free space in my sump... I used a calculator that may not be worth a hill of beans that said I needed 15G of sump volume to handle my proposed flow rate. So 15+10=25, add another 10% or so for pipe volume, so I'd guess I need a sump around 27.5 Gallons... So I'd probably build my sump out of a 30G tank...


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## hotwingz (Mar 3, 2013)

I admire your ambissions! This is a big project. I'm decently handy but making a tank out acrylic is huge. I do agree that an overflow this big would be way more than needed. Now I don't necessarily feel that you can overdo when talking filters. And I do like the idea of mounting your overflow box like that. I'm sure if you have the water movement your looking for you would not need to have that much area for overflow. Especially if your going to do FW than its not as important. But even salt tanks don't have more than two corners or one large center, not that I've seen anyways.


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