Internal Sump Design Ideas

[littlejohn657]

I'm contemplating building a narrow internal sump along the back wall of my long 20 gal freshwater aquarium (12x12x30). Because of where I live and the set up I have here, I can't set up an external sump, but I'd like to get something better than the pop bottle filled with ceramic pellets connected to a pump that acts as a surface skimmer. I could use some feedback on this idea please; sorry.

I've been seeing some debate on how sumps should be set up, and what should be used as filter media. I was thinking of building it from acrylic (I was hoping for black, but I'm not sure where I can find that where I live), welding the baffles to it, then siliconing it all to the glass (because it's only for a seal and not for structure, I'm not too worried about how well the silicon bonds to the acrylic). I'm going to set it up with an overflow weir in the one corner, draining onto some filter media (a coarse foam then polywool, unless I can find something better). Next, I want to run over some type of bio media like bags of ceramic pellets or volcanic rock. Next bags of activated carbon, followed by a heater and UV sterilizer. The last step is a wet-dry section filled with bioballs or pot scrubbers to provide some aeration to the water (I'm told it's relatively quiet, especially compared to an air pump). Each of these sections would be supported from underneath by some type of grate like a light diffuser. Then the water would be pumped back to the tank through an undergravel jet system to reduce the current for any fancy-tailed fish and improve substrate oxygenation.

Here's the issues I'm not sure on. I've heard mixed opinions on whether or not the baffles need to be set up to have the water flow from the top, or whether it's fine to have water flow from underneath (the latter would save space). I've also heard there can be some issues with using activated carbon in the system, and that it is associated with some diseases in fish, but I've also heard that is a myth. I'm not sure how to calculate the size of the notches for the weir, and I don't have access to a table saw to actually cut the notches (and drilled holes don't seem to do surface skimming as well). And lastly, I'm contemplating doing some aquascaping in this aquarium, so I'm wondering how well this system would work with that, especially with an undergravel jet system (this will also be affected by the type of substrate I use I expect).

So, any feedback on this idea? Thanks!

 

[littlejohn657]

Also, I'm wondering about putting a CO₂ system in the sump. I could move the UV sterilizer and heater around, and put the CO₂ diffuser in the open slot. That would hide the equipment and leave a cleaner tank look. The question I have there is whether I should do that where the water is going up or down in the sump. I'm also wondering if putting the CO₂ diffuser in the sump is a good idea, especially before the trickle section, as well as when the water is being pumped back under the substrate.

 

[littlejohn657]

How about attaching the CO₂ to the powerhead outflow and diffusing it into the aquarium that way under the substrate?

 

[dougall]

You are purposefully designing the sump to aerate the water... this is counterproductive when it comes to dissolving CO2 in the water... I would suggest you pick one.

Personally, I think this would be too small of a tank to try to attempt so much.

I doubt you need everything you have listed there, maybe think about what you will actually need, so that functional places may have more available space to work correctly. For a personal tank, I'd likely lose the bioballs, UV sterilizer, heater and the carbon, and chances are I would look at a corner mattenfilter.

 

[littlejohn657]

Thanks for the feedback Dougall. I agree, on a 20 gal, getting everything in there will be very challenging, but I'm already pushing the spirit of rules where I live with this for a tank ("small fish only"), so anything more might be tough to get permission, and I'm not allowed to bring in extra furniture. Feel free to critique my arguments though; I'm still fairly new to some of this stuff.

There are a few problems with doing a Mattenfilter. This is in my bedroom, and I'm trying to keep the noise down by not having an air pump if I can avoid it (I can't hear my current system at all unless the water gets low). I also can't use something with a high current, as I have fish with long tail fins, so directed outflow won't work. If I want to try aquascaping, I can't put much pressure on the sponge with hardscape or substrate. I'd also like to try keeping the water levels in the visible aquarium more consistent (even though that may mean even more frequent water changes and top ups). I also have to limit the amount of That's why I'm looking at an internal sump over something like that.

I have the same thoughts about the use of the bioballs. I'm worried the CO₂ will be lost due to the agitation flowing over that, but I'm trying to figure out how to make sure I have enough oxygen for the fish and reduce anaerobic areas in the tank. However, I suppose if I have enough plants, they will be producing enough oxygen for the fish, but it would be nice to have a good way to get oxygen into the water without using a bubbler. Putting a trickle tower as the last step I figured would quietly improve oxygenation without needing a bubbler.

I think running a heater is something I should already be doing with tropical fish, but I've been lucky so far I figure. My room is maybe 20°C (68°F), which is a bit cold for tropical fish, though the temperature does vary.

I'm debating whether I need the UV sterilizer. I was starting to think I was having too much algae in the water column, even with water changes and a really low bio-load, but the otos and shrimp I recently picked up seem to be helping with that problem. However, due to the set up in my room and the house plants I have, the aquarium gets direct sunlight for at least a few hours a day, and there's not much that I can do about that, practically speaking. And if I set up a light on the tank, and with increasing the fertilization for the plants, algae could become more of a problem.

I really don't know if I need carbon filtration. There's a lot of debate about whether this is really needed in aquariums. There are also a lot of aquarium systems that don't use it. If I wanted to, I could remove this and add more ceramic to increase the bio filtration. I could also remove this and increase the free space I have to work with.

 

[dougall]

a mattenfilter does not need to be driven by an air pump... basically anything that will move water will work.. a small pump or powerhead to get a current through the sponge should suffice.

If you have plants growing, and are not overstocked, I doubt that the animals will need extra oxygen... trickling will create noise too... which seems to be something you don't want. If you do need to oxygenate the water, can you divert the output from the pump to break the water's surface?


It sounds like a heater may be needed, but will ultimately depend on the stock chosen.

Having plants may help your algae problem, but the algae needs to get nutrients from somewhere.. so maybe double check your feeding regimen too, and check the source of your water for things like nitrates. Having terrestrial plants, like pothos, gwrow with their roots in your tank may help with algae issues too. If you think you really need UV sterilization.. is there a reason to not use something like a hang on back unit (I know cobalt makes one for example) to just run occasionally.

I'd keep the technology down as much as possible.. I don't know your setup, but is it really impossible to use a small canister?

 

[littlejohn657]

I've attached a picture of my current set up. Sorry, it's evening here, so the lighting isn't great right now and everything looks much darker and dirtier than it actually is, though it does need some cleaning.

Part of why I am looking at an internal sump across the back is that I wanted to maximize the amount of view I get across the front of the tank, and create a uniform background. I can also hide all of the equipment in the sump, leaving a cleaner view of the tank in general. Because of the limited amount of space I have in my room, I am trying to make things as colourful and living as I can (which is why I have such a large plant set up too; I've included a picture of that, though a few plants missed being in the shot, and I use water from the aquarium to water them, but I digress). By doing all of this, it should create the sense of being larger and more open that it would otherwise.

I might be able to divert the flow so that is breaks the surface, but again, I need to keep the noise down. I'm also limited on how I return the flow to the tank, as my betta really doesn't like high flows and current, which you often see with a lot of return systems that break the water. The last time I used a small internal canister filter, both with the stock return and also with the same diffusion bar I use now, he would hide on top of the canister to get away from the current, which is why my current powerhead is a bit under powered, but seems to work for my low stocking). I'm hoping switching to an undergravel jet return system to help reduce the current further, but that makes it much harder to do with an internal canister due to how they are constructed, and I don't have any room for an external canister.

I have some good idea about where the nutrients are coming from. I do try to limit the amount I feed my betta (he had the aquarium all to himself for a very long time), but I know I do overfeed him a bit. I had hope the two phalaenopsis orchids I am growing aquaponically would keep the nutrient levels down, but I'm not sure how much they are actually consuming from the water being orchids and all. Some of the roots in the water are also breaking down after they die, which adds more bioload in the water. The orchids have been doing really well though, and they've been growing this way for the last four years, but I'm digressing again.

True, a trickle system will add noise, but from what I understand, it's not that bad. The bioballs or similar material break up and slow the flow, so there isn't the same level of noise as there would be if that section were empty. And if I have any kind of top on that area, it should help to reduce the noise further.

I think you might be right about the UV sterilizer thing. I can always create a spot for it if I have the room, but not install one until I know if I need one. I am worried it might affect the colonization of the filter media, so I wouldn't want to run it for the first while at least. I'm also worried about the power I have here, as they put this room and the one next to it on the same breaker, so I've been tripping the breaker when I try to use my printer. And from looking into these, it looks like they are designed for aquariums that are having a lot more trouble with algae than I have (the worst my water has ever been in terms of being green and cloudy hasn't ever been much worse than this, but it's still greener than I like). It's also hard to find a unit rated small enough for a tank this size. If I improve my algae control, I likely won't need a UV sterilizer. And if I do change my mind and want to try one down the road, I'll see if I can find one with a powerhead that will allow me to replace the powerhead I was going to use anyways.

And going back to the carbon for a moment, I'm still questioning that one too. Carbon takes a lot of stuff out of the water that plants need to grow. If I'm using any kind of fertilizer, I'm also going to be losing a lot of those micronutrients as well. I'll probably skip on that and maybe switch to more biomedia in its place. If I find I need some, I can always add some to the system afterwards.

 

[dougall]

It is still early morning, and I am not terribly awake.

But from what I can see there is a betta and some otocinclus?

The betta is an anabantoid, and can breathe terrestrial air, so no aeration needed.. the otos shouldn't have too big of a need.

Personally, if it we're me and I insisted on having a certain amount of 'trickle' I would lower the height of the baffles, not include ceramic, or carbon, or UV, or bioballs and just have the water flow through the weir a bit, into a block of foam, or maybe 2 larger pore then smaller. Bacteria will colonize them just fine, then have your heater, maybe another part for floss if you like which you could remove and replace with a bag of carbon if you had a need for some, and then the return pump..

If you did want to use an undergravel filter, you can drive it with a powerhead just fine, you could reverse the flow so that the output goes through the gravel and use a Venturi to add air.

As an alternative, if you look up some stuff by Oliver Knott, he has done plenty of things using a fake decorative background in a tank, and using it like a sump to hide equipment, so that might prove useful inspiration too.

 

[Narwhal72]

I have a lot of experience with this type of setup and I can tell you right off the bat you are going to have problems installing it.

A key aspect of back wall filtration is that the internal baffles must seal to the bottom and back wall. Your aquarium already has a bottom seam running along the bottom which creates an irregular edge that your baffles need to seal against. Plus the area is in a place where you can't run the seam with your finger to smooth out any edges. When these types of filters are installed they are installed when the silicone seams are still wet so that the baffles can fit smoothly against the glass. It will be impossible to get a seal unless you strip out the bottom and side seams and reseal it as you are installing the new filter.

Your filtration is overkill for the size tank you have and you are going to lose about 1/3 of your tank volume to the filtration chamber. It really does not seem worth it for a tank that size just to have a solid background.

I would suggest going with a corner mattenfilter and just installing an acrylic panel in front of it (with slots for water to pass through) and along the back panel. This will give you basically the aesthetics that you are looking for but be much more practical to install and use.
Andy

 

[littlejohn657]

Thanks for the feedback Andy.

Part of the reason I want to increase my filter media is because I plan to increase the number of fish I have in the aquarium. You're right -- for the amount of fish I have, yes, the media will be too much. But if I double, or even triple the number of fish I have (likely very small fish I do the latter), I'm going to need a lot more filtration and water flow than what I currently have. Planting can help with reducing the nitrates, but I need media to run the nitrogen cycle (I estimate only 2.5-3 litres of media in this design). From what I can see, Mattenfilters also aren't going to do much for surface skimming, which is one of the bigger issues I currently have and why I want some kind of overflow/weir (which is also why I was going with notches rather than holes). And with the size I am looking at, I estimate I'll lose at most a quarter of the volume of the tank to the sump.

For the seal on the bottom and the sides, I was planning to leave a 1/16" gap around each edge where it meets the glass in order to get silicone in the space to get a good seal all around. and round over the corners of the acrylic so that they create a better fit in the corners of the aquarium. I was also planning to pre-silicone the baffles and the bottom and fit them in while the silicone is still wet so I can get a good seal with less problems if I can't fit something in there to run along the seam. Moreover, with my latest design, I can see only one, maybe two spots where I won't be able to fit my hand, but I should be able to fit some kind of squeegee tool in there to run the seams if I have to.

One concern I do have with this design though is that I will need to keep a close eye on the water level in the sump. There isn't a large head of water over the pump, meaning that it could run low quite quickly if I don't keep an eye on it. But, that's also more incentive to do frequent water changes.