# Sealed Sump Design Advice / Comments?



## AaronT (Apr 26, 2004)

I've been learning a little sketchup and designing a new sump for my tank based on a standard 20 gallon high aquarium. The idea is to have a weather seal around the rim and hold downs to secure the lid on the seal. This should allow for a good seal without using duct tape each time.

I'm thinking I'll use aluminum for the holddowns as it's cheap and relatively easy to machine. Will aluminum epoxy to the plastic rim with JB Weld?a

I could also use nylon or acrylic.

The area on the far left is in case fish / shrimp get sucked up they have a place to live until I scoop them back out.


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## BruceF (Aug 5, 2011)

Nice design. I find I do all my dosing and such in the sump and having access is kind of handy. I would think you could use a reptile screen top and just put a sheet of Plexiglas in or over it. But your design is much more elegant than my thinking.


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## AaronT (Apr 26, 2004)

BruceF said:


> Nice design. I find I do all my dosing and such in the sump and having access is kind of handy. I would think you could use a reptile screen top and just put a sheet of Plexiglas in or over it. But your design is much more elegant than my thinking.


Well, the dosing can be done on the right side of the sump. That part is the wet side and is open on the top.


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## BruceF (Aug 5, 2011)

OIC. So just the trickle part is enclosed.


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## niko (Jan 28, 2004)

What is the purpose of sealing the sump? If it is about CO2 escaping I am not convinced you need to machine aluminum to save a few bucks and complicate your life.

Epoxy will hold on some plastics better than others. Not on nylon. If you want to use it you need to sand the plastic with 80-180 grit sandpaper and wipe it clean with acetone, xylene, or lacquer thinner. JB weld sets real fast so plan on how exactly will you apply it quickly.


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## AKnickolai (Nov 30, 2007)

For the CO2 conservation, I found that a supple neoprene gasket applied to the rim of the aquarium and then a small amount of weight (I used a rock) was enough to significantly reduce losses. Might be a simpler solution, I originally wanted to go the clamp route as well. 

It looks to me like the wet/dry portion is going to be filled with foam (maybe that is just because bio-balls etc would be a pain to draw). If you are going all foam, why not just go simple with multiple sheets of Poret across the tank for mech and bio filtration? The reason I ask is I am having a similar debate in my mind about my next sump.


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## AaronT (Apr 26, 2004)

AKnickolai said:


> For the CO2 conservation, I found that a supple neoprene gasket applied to the rim of the aquarium and then a small amount of weight (I used a rock) was enough to significantly reduce losses. Might be a simpler solution, I originally wanted to go the clamp route as well.
> 
> It looks to me like the wet/dry portion is going to be filled with foam (maybe that is just because bio-balls etc would be a pain to draw). If you are going all foam, why not just go simple with multiple sheets of Poret across the tank for mech and bio filtration? The reason I ask is I am having a similar debate in my mind about my next sump.


Yes, the purpose of sealing the dry trickle side is to conserve CO2. It really does gas off a significant amount.

Yeah, I thought about doing a wet sump as well, but couldn't figure how to seal the top because of power cords and such coming out of the top. I suppose I could drill it for the heater and pump, but that sorta defeats the purpose of having both of those easily accessible.

It will be poret foam. I'm already using just poret right now and I love it.


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## BruceF (Aug 5, 2011)

Where are you going to add the co2? 
I have three tanks linked together. One is a wet sump the other two are planted. All three are covered except where the overflows and return enter and exit the tanks. So there is a two square inch or so cut out of the plastic piece on the lid where I also run the electric cord for the pump. I found that between the pump and the light I don’t need to use a heater. 
I don’t know about off gassing co2 but one thing I have noticed is there is essentially no evaporation. The tanks I do have with no lids lose about an inch of water a week
I really don’t know but I would have to think you will lose more co2 in the open area than you would retain in the wet dry part. I would be interested if anyone knows how that would work.


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## AaronT (Apr 26, 2004)

The CO2 will be fed directly into the return pump.


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## AaronT (Apr 26, 2004)

niko said:


> What is the purpose of sealing the sump? If it is about CO2 escaping I am not convinced you need to machine aluminum to save a few bucks and complicate your life.
> 
> Epoxy will hold on some plastics better than others. Not on nylon. If you want to use it you need to sand the plastic with 80-180 grit sandpaper and wipe it clean with acetone, xylene, or lacquer thinner. JB weld sets real fast so plan on how exactly will you apply it quickly.


I'm hoping to save more than a few bucks on CO2. I'm running pretty high light at about 140 PAR at the substrate level for 5 hours a day.

I'm running a traditional wet dry right now with the CO2 going into the return pump and I burn through a 20 lb. tank in 6-7 weeks. At $25 a refill there's quite a lot of money to be saved. Not to mention the hassle of driving through the industrial district and finding the time to do so with 3 kids.

Good to know about nylon. I had my suspicions because it's so slippery. You aren't kidding about JB Weld setting quickly. I may just go with acrylic.

Someone on another forum had an idea to bevel the edges of the acrylic lid so it can be fit in the seal using a little compression.

Also, when I say I'll be machining what I really mean is I'll design and give my Dad to machine on the CNC at work.


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## BruceF (Aug 5, 2011)

One thing I did find was that it was easiest to regulate the flow by having a branch of the return pipe return water to the sump so that the pump itself could run at full throttle and I could increase and decrease the amount of water that returns to the tanks. I am thinking I may build a reactor to take advantage of this branch but I haven’t really gotten that far.


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## niko (Jan 28, 2004)

Hmm, still not convinced that saving CO2 by sealing off the sump is the best way. From my experience the CO2 can be dialed way down depending on how you disperse it in the tank. Have you done your best to diffuse the CO2 the best?

Another thing that kinda bothers me - the idea of a sump is to take advantage of the air which helps the bacteria. With CO2 taking up some of the space the idea of an oxygenated biomedia is shot down a little. How much I do not know but you get my drift. Wouldn't you get the same efficiency if you just submerged all the biomedia in water and preserved CO2 that way so you don't have to make a lid for the sump?

If I understand you correctly you intend to just glue the lid over that sump using epoxy. If that is so then go for a different design - one that you can fully disassemble.


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## AaronT (Apr 26, 2004)

niko said:


> Hmm, still not convinced that saving CO2 by sealing off the sump is the best way. From my experience the CO2 can be dialed way down depending on how you disperse it in the tank. Have you done your best to diffuse the CO2 the best?
> 
> Another thing that kinda bothers me - the idea of a sump is to take advantage of the air which helps the bacteria. With CO2 taking up some of the space the idea of an oxygenated biomedia is shot down a little. How much I do not know but you get my drift. Wouldn't you get the same efficiency if you just submerged all the biomedia in water and preserved CO2 that way so you don't have to make a lid for the sump?
> 
> If I understand you correctly you intend to just glue the lid over that sump using epoxy. If that is so then go for a different design - one that you can fully disassemble.


I may still go with just a wet sump like you described where the foam panels simply divide the sump and the water must pass through them to the return pump. Sort of like an open canister filter with the benefits of hiding equipment and keeping the tank water level consistent.

No, I plan to glue / epoxy the hold downs to the rim of the tank. The lid would be held in place by the bars going across it and the wingnuts on the hold downs.

There is still some oxygen introduced into the system via the overflow. Quite a lot compared to a canister intake still I would say. I know folks running surface skimmers on their canister filters and they had to bump up CO2 a little bit then too.

You are right about better diffusion. Right now I just feed the CO2 into the return pump. I'd like to build a venturi reactor to sit inside the sump that then feeds into the return pump. That's also on the to-do list.

I may also play with my light height to bring the PAR down a little bit. Honestly though, I like having high light and fast growing plants. I know that's not your thing and that's okay.


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