Advice on sump design

[cdearing]

I purchased a used 55G tank and stand to replace my 29G. I want to build a sump or sump refugium to put in the underneath cabinet space. I will have to do some retrofitting of the cabinet to make it fit. I am thinking a 20G sump. If I go bigger, I will have to remove the middle board (see photo) and risk the strength of the cabinet. Maybe I could put some metal braces inside. I don't have a sump now on my 29G so appreciate any advice on sump and/or sump/refugium design. I have read a bunch about sump design and watched several videos on youtube. It's still a daunting task. Would the benefits of adding a refugium be really worth the effort? I have a Remora C Pro skimmer and will have at least a 3 inch aragonite sandbed. I know I will need to purchase a continuous overflow as the tank is not drilled. I plan on cutting off the sides of the tank so that the sides of the tank are in full view and the hood and cabinet will be seperate. Please give me your opinion based on the included photos.
Cabinet dimensions are 49 long by 13 deep by 31 high. Thanks, Cyn

[cdearing]

This is how the cabinet looks now.


I will be removing the fluval.

From the back;

[charlie]

I think if you cut the board out of the middle, and left the uprights on the edges, you would be fine. You could always have your dad reinforce the bottom with a chunk of plywood also. A couple of extra 2x4s around the edges probably would hurt anything either. Just my .02.

[Nemo Keeper]

I think Charlie is on the money here. I would definitely re-enforce the bottom to support the weight, other than that, sounds like it would look nice

[Seige]

Looks like a decent cabinet. Don't think I'd cut the middle brace unless you also reinforced it.

[cdearing]

What about a couple of angle irons? I could get that at Home Depot or Lowe's. If it would stop snowing!!!!!!! I might be able to get started on this project.

[Future]

Looks like 3/4" plywood, so if you cut out that middle brace, yes definately go with a good size. 3/16 should do the trick, but you'll need 1 for the horizontal and 2 for the verticals. If you're going to weld it, you can do angle iron for the sides and a flat piece for the top support. Just make sure the welds are clean and sealed properly.
You could even do a full inner support to keep the wood from bowing. That would be the way I would do it.

[cdearing]

Sorry if this is a stupid question but...

Can I put an HOB skimmer on a sump?

Does everyone have a bubble trap on their sump? If not, what do you use to get rid of bubbles?

[Seige]

Sorry if this is a stupid question but...

Can I put an HOB skimmer on a sump?

Does everyone have a bubble trap on their sump? If not, what do you use to get rid of bubbles?

Don't see why you couldn't...

I don't even have a sump yet. Just bought my sump tank. Plan to modify it this week by adding the bubble trap, etc. My skimmer is an in sump model but I'll be using it as HOB because my sumps too small for it. I'll need to seal the skimmer and place it in some form of container just in case it leaks. The LFS here uses the same in-sump model as a HOB without any issues so I hope mine will work out ok.

[cdearing]

I hope that you will keep us updated on the progress on your sump. I would love to see photos of how you put it together.

I have been reading so much about sump designs that I'm cross eyed and confused.

[Carissa]

When I made my 20g sump I put one tall baffle from bottom to top for the height of my skimmer at one end of the sump. That overflows into the next main compartment that has one bubble trap baffle (also comes in handy for adding media of some kind). Make sure you design it so you can leave enough room in it in case the power goes off and water back siphons into the sump. Also drill siphon break holes in the top of your return pipe. It's easy for me to determine how full to fill it since full is directly at the top of the bubble trap. If I fill it fuller than that I'm at risk of an overflow if either the overflow box stops functioning or the power goes off.

[Seige]

Make sure you design it so you can leave enough room in it in case the power goes off and water back siphons into the sump.

That's what I was planning but wouldn't a one way valve on the overflow and return pipe solve that problem too?

[Carissa]

No. It would prevent the entire tank from back siphoning in case of a power outage. But drilling siphon break holes on the top of the return pipe would do basically the same thing if you make them close to the water level, and then there's no chance of a valve failing. You still have to account for the volume of water that would siphon out of the overflow box into the sump in case of a power outage so the sump could not be totally full for that reason as well. A one way valve from the overflow box would be allowing water to go down into the sump, so there's not much use there. There's no way that water will reverse itself up from the sump into the tank from that route anyway, necessitating a one way valve.

To prevent the pump from filling up the display tank if the overflow box stops working, I have the pump sitting close to the surface of the water in the sump. As soon as the water level gets too high in the display tank, the pump starts sucking air, thus preventing an overflow in the display tank. This has already saved me a number of times when I was messing around with my overflow box and restricted flow inadvertently. It also reminds me to top up the water, if it evaporates too much it starts sucking air as well. I don't know if this is the best way to do it but it works for me.

[denhay14]

I've been watching youtube videos of this guy who seems to be really good at aquarium stufff, and he shows you how to make a sump. He doesn't make anymore videos at the moment since his video camera broke but he has like 20 videos.

DIY Sump part 1

DIY Sump part 2

He also has other very useful DIY methods so might want to check him out ;-)

[Seige]

A one way valve from the overflow box would be allowing water to go down into the sump, so there's not much use there.

um ya... lol I didn't think about the whole process. I'll likely add a one way valve on the return since I'd practicly have to keep the sump dry in order to absorb water from both pipes

To prevent the pump from filling up the display tank if the overflow box stops working, I have the pump sitting close to the surface of the water in the sump. As soon as the water level gets too high in the display tank, the pump starts sucking air, thus preventing an overflow in the display tank.

Won't your pump burn out from sucking air? Wouldn't a float switch be a better option to shut down the pump. You could add an ato drip system or ato on a float valve.

[Carissa]

A float switch might be a better option. But it doesn't happen very often, and I don't have a float switch. One of these days when I come across one I'll probably get one. It doesn't actually run totally dry, it just gets to the point where it's sucking enough air that it can't pump the water up anymore. When it starts sucking air I shut it off right away. Theoretically it could happen while I'm gone if there was a sudden failure in the overflow box.

[Ninong]

I purchased a used 55G tank and stand to replace my 29G. I want to build a sump or sump refugium to put in the underneath cabinet space. I will have to do some retrofitting of the cabinet to make it fit. I am thinking a 20G sump. If I go bigger, I will have to remove the middle board (see photo) and risk the strength of the cabinet.

Did you purchase the stand from an aquarium shop? The reason I ask this question is because I'm wondering how much experience they have with that exact design. In other words, are there a lot of stands out there like that that have held up over time?

Like Charlie, I would be nervous about the way the stand's tank support table is cut into the upright sides of the stand. I would feel much better if the plywood sides were fully under the tank support table thing. Either that or they could have built some sort of support structure inside the plywood facing. It wouldn't have to be 2x4s for this size tank, 1x3s would have been fine (IMO).

Do NOT remove the center upright plywood. That would positively lead to disaster. Don't forget, you're asking this stand to support several hundred pounds. Seawater weighs approximately 64 pounds per cubic foot and there are 7.48 gallons in a cubic foot. So seawater weighs ~8.55 lbs/cu ft (varying with salinity). On top of that you have to add the weight of the empty tank itself, the weight of the sand bed, the weight of the live rock, the weight of the light fixture (if it rests on the tank), the weight of any powerheads, etc. So you're asking this stand to support more than 500 lbs.

If the store has sold lots of these stands without having people report failures, I would feel a lot better. We hobbyists have a tendency to go for overkill when we built our own stands but that's because we take one look at what's offered in stores and freak out. In any case, do not do anything that would weaken what you already have.

I don't have a sump now on my 29G so appreciate any advice on sump and/or sump/refugium design.

Mark has lots of DIY sump designs in various sizes, plus instructions on how to build them, on his homepage.

Would the benefits of adding a refugium be really worth the effort?

By all means, include a refugium section if you can. If not, then it's no big deal. It's just something nice to have and it definitely adds additional benefits to your system, provided you have room for it.

I have a Remora C Pro skimmer and will have at least a 3 inch aragonite sandbed.

Excellent!

I plan on cutting off the sides of the tank...

Isn't that a typo? You can't possibly mean that you are going to cut the tank.

...so that the sides of the tank are in full view and the hood and cabinet will be seperate. Please give me your opinion based on the included photos.

Do NOT make any structural changes to this stand at all, unless you're making changes that reinforce it. I would not start cutting it up if I were you. And I think you should ask the people who sold it how many they have sold just like this so that you will be able to sleep better.

Can I put an HOB skimmer on a sump?

Yes.

Does everyone have a bubble trap on their sump?

Yes, all sumps have bubble-trap baffles.

Good luck!

[metalhead]

I agree... Do not start cutting on your stand and/or removing braces or you will be asking for big problems.

[CharlotteSteve]

Hmm I'm interested now. Lets say ~640lbs (470 for the water, 78lbs for empty weight, 50 lbs of live rock and 40 lbs of sand). Oak has a ultimate tensile strength of ~60 MPa. Making a close estimate of surface area the tank will be supported by I would say around 63 sq inches or .04064508 sq meters of support total (three cross members and the back part). Luckily the flat wood on top will distribute the weight quite nicely, so we wont bother with that. Convert lb force to newtons and we get 2846.86N. Divide the two and you get 70042.117 N/m^2 or Pa. Sounds like 60000000 Pa will do quite nicely. I think that your house will sink or the thing would explode at the sides at max weight.

Lets see what happens if you take out a center beam. That would back the cross sectional area to .032581 m^2. So divide the weight into this and we get 87377.976 Pa, still good to go.

So it seems in this design that the members keeping the sides "in" are going to be more important than the compresive strength of the wood. Basically the wood will hold 60MPa if it is kept prefectly rigid. So any torsions or uneven loading may result in failure. The formulas to solve this are endless due to the multiple scenarios. Also, as I am sure some of you will be quick to point out, the two short sides and the long back are attached to the wood via screws/nails. This is scary due to the shearing force of the screws (a whole heck of a lot smaller than the woods tensile strength, depending on the amount of screws and theyre cross sectional area) or pulling the screws out. I would seriously suggest, atleast so that I can sleep at night, to brace directly underneath your tank or the flat board that is holding the total weight. This is very important in salt water applications. I recently took a 10+ year old stand apart to scrap the wood, I broke every screw trying to get it out due to the rust from the salt water, yeah it was holding up 500 lbs of weight, but it wouldn't have been much to make it fail.

Please someone check over my math, I did this on a napkin at work.

[cdearing]

Yea...thanks Steve...I'll check your math and get back to you...
Meanwhile, I have someone coming to look at my stand this weekend to let me know what can be done with it.