Freshwater refugium?


Being honest, I really want to make my own one out of AC 500. But what kinds of plants, algae and mashroom should I keep in it?

I figured it could be cool to have one because it will take some of the nitrate load, but more importantly and intresting is TO GROW MY OWN FISH FOOD/TREATS!

I just want to try, at the worst I lost like 20$.

Any tips & suggestions?

Is that such a bad idea? No one have any knowledge about it?

Merged back to back posts.


I wanna build a sump/refugium for my new 6foot tank. Sorry I can't really help with plant suggestions as I haven't kept a planted aqarium before... Go for it dude


I'm not sure what an AC500 is...

It's a very interesting idea to grow your own fish food through your tank. What kind of fish do you have to feed? And what foods do you have in mind? I can't think of any plants at the moment. I've only seen these two-in-one tank set ups for keeping incompatible fish.

Good luck Itamarironi!


My fish are ten neon tetra, two pearl guromi, one kuhilI loach, one bamboo shrimp and one cherry. The AC 500 is the 110 one (500 gph)

I know how to build it, but wondering what soil/substract to use + what to plant in it? Or maybe use it to breed a kind of live food?


ive found thhat the following plants tend to work well for me in freswater refugiums in a broad range of conditions : java fern, java moss, phieonex moss(fissedens sp.), anubius sp., riccia. how well they work will depend on ph, light levles and cycle, nitrigoen load. I do not use supplemental co2 on mine and they do just fine(as long as water flow incomming is low and not hevily difused.
I also use the following inverts to control algae in my freswater and brackish refugiums species used depends on ph,hardness and in the last case salinity: amano shrimp,cherry shrimp,nerite snails,gammrus,ostracods,cylops,isopods(good for cleaning up decaying plant matter)
depending on size and plant species used substrate may consist of laterite,large chunks of lavarock,standard aquarium gravel or a mixture of the above
am currently using a 4 bulb led nano light(6500k) for both of my freshwater refugia.


things I forgot to add

all the invert species listed also make good fish snacks. a couple others I have used in past are ghost shrimp,ramshorn snails both tend to breed well. fingernail clams(tend to do well with a smaller substrate),and daphnia both of which are filter feeders ony tend to do well for me if green water is ocasionaly present.
if your refugium is open topped and have suspended lighting you are not limited to aquitic only plants. there are many emergent plants that will do very well with just wet roots.
hope this was not too long as this is my first full post response


Hmmm, what an interesting idea....I have an AC110 being stored in an empty tank.....


Not sure how effective the slow growers would be with nutrient uptake (java fern, anubias), but they would still make a great hideaway for live foods.

If you replace the impeller on the AC110 (AC500 if it's an older model) with the impeller from, say, an AC20 or AC50, you can slow the flow way down. This is good for maximizing contact time with whatever plants you are using for nutrient uptake.


Good tip, thanks

What kind of food can be grown in it?


Well, that's the way we salties do it, anyway.

I've never tried this with a Freshwater tank.


great idea harpua I would not have thought of switching out the impeller to an older type to reduce flow.
there are many other fast growing plants that would be better for nitrogen uptake water sprite,combomba,hornwort,anachris,baccopa,ludwigia,etc.but these tend to require frequent thinning and need higher light output. also floating plants such as duckweed,azola or sylvania only drawback to floating plants is they quickly block light out to the submersed species and somtimes in the case of smaller ones like duckweed may clog outflow.water hyacinth could also be used but would require a lot of light ouput and a large refugia with room for emergent vegetation. and as long as the tank is not heavily overstocked with fish is mostlikly overkill.
and to jaysee all the inverts I mentioned in the earlier post make decent fish food along with some of the plants i.e. riccia,duckweed,and any of the softer bodied plants. have done with anachris when I had my uarus made nice supplemental veggie feed when thinning.


I was just wondering if people ever had a refuguI'm tank for their freshwater tank to filter their water. I was just interested in this because you get to do less water changes and stuff.

this is what got me interested skip to 6.50 if your lazy


It's a great way to control nitrates, which can be a nice DIY project.


I think the refugium is a very good way to filter a tank. There are several benefits to running a refugium, one being it adds extra water volume for the fish without having to have a larger tank. You can accomplish a visually fuller looking tank this way.

My main beef is the idea that is often presented in that you don't have to do near as many water changes because the nitrates stay low. There are really so many more reasons for providing water changes than just to lower nitrates. Unless there is always a full variety of minerals being supplied to the tank, the fish and plants will suffer from deficiencies. Some of these deficiencies in fish aren't easy to diagnose and are often misdiagnosed as some other type of disease. Fresh water provided by water changes helps to maintain that constant supply of minerals and it really takes the need out of trying to figure out what types of minerals you should be trying to add to the tank. Water changes are a cheaper way to provide these minerals than having to buy other sources. Fresh water takes much of the guess work out of these things and can only benefit your fish.

I think the worst reason to have a great filtration system of any kind is to avoid water changes. It's best to do both. Have a great filtration system, one you can understand and maintain properly AND regular large water changes. That way your fish get to enjoy the best of both worlds.


Is a refugium like a fresh water version of a saltwater sump?


A refugium is a separate little eco system that feeds to and from the main tank. It uses mechanical as well as biological filtration. The water is usually cycled threw the refugium quite slowly in order to allow more contact time with the biomedia. It's designed to grow plants and algaes in it as a part of the whole filtration system so it uses a light to promote life and growth.

A sump is more designed to keep the water level the same in the main tank at all times and provides more water volume for the fish. It provides an area to use heaters, thermometers, skimmers, and other equipment without cluttering up the appearance of the main tank. It isn't designed to promote life so no lighting is required.

I'm sure there is more than just this for differences so maybe somebody else will have more to add.


I see, I always though sumps were used to support extra space for bacterial growth so you could support higher bioloads . I was wrong lol. Thank you for the detailed responce


No, I don't think you were wrong. I believe sumps do use bio balls or other bio media, but beneficial bacteria doesn't require light in order to live. The fact that there is bio media in a sump, as well as extra water, means it does help with higher bioloads. It doesn't necessarily help with nitrate levels though, and because of the benefits of plants in a refugium, nitrate levels are able to be naturally kept lower.


I know this means I have to make one now right? I could see how this could be useful with high stock tanks like cichlids, or larger tanks that are harder to do large WC on.


Hi, I've moved this topic to the Advanced Freshwater Topics, as it is a not-so common Freshwater approach.

As for sump vs refugium - many sumps incorporate the refugium as a section, so the two terms are often mistankingly used synonomously. Toosie's description is pretty much spot on


Do lots of research because there is more to it all than what I have explained. I only touched base on the type of refugium the OP is asking about which acts as the filtration system for the main tank, and it sounds like the type you may want to try. There are other types of refugiums out there that aren't intended to be a part of the filtration system.

I think most sumps utilize a wet and dry type of system for filtration, but again, there are probably different ways to set one up.

I'm not an expert on either of these systems so I know there is a lot I don't know about them, but I've tried to tell you as much as I could. Research them as much as possible so that you can design one based on your needs, and please don't use them as a substitute for water changes or gravel vacs because those things are still very important.


No worries, I understand the concept, just wasn't sure the difference. There is no substitute for WC or regular maintenance.


I didn't realize you could actually buy these things you would have to do the plumbing and get the plants for the refugium though.


You can buy anything....for the right price


It can and will work, I can verify this not form a fish point of view but from chemistry and work. The plants will do a wonderful job just be sure to select plants appropriately as you really don't want to have to add to the tanks to keep them working well. Most times you will see simple plants in a setup like that.

I have been looking at going a bit more complex but as a separate tank and that's just a whole different ball park even.


Good morning,

Starfuel1, I am moving your post and related posts to create a thread of its own. I will post a link to your new thread here in just a moment.



Here is the link to your new thread:


wouldn't a Freshwater refugium just be a aglae scrubber?


I think it's a great way to filter an unplanted (or even planted of course) tank!

If you have an algae problem in the tank due to excess nutrients, and your new refugium can then out-compete the algae for nutrients, then I believe the refugium would act as an algae scrubber. However, the refugium will also work to keep water quality cleaner as well which is the main bonus.

I have a silver dollar/severum tank that I've been meaning to do this to. I have a big wet/dry filter with plenty of room for plants. I just need to get around to buying a light for it and then I'll have my refugium going. It's a 180g and my only permanently non-planted tank... it seriously needs some plants for the nitrates so I'm hoping the refugium will make an impact.


I really want to act on an idea I thought I had originated but have seen them done very similar to what I want to after some research.

I want to build my own plant bed next to my 29 gallon planted tank. It would be a wood box basically built around a plastic box or possibly just a 10 gallon or 20long aquarium, anything really. I would fill the refugium tank with water and put some eggcrate layered near the top for the roots from household plants and some semi-aquatic plants to grab.

I then want to run a siphon from main tank down to the refugium. water would run through the roots and the nutrients would be sucked up by the roots of these plants. Water would then be pumped back into main tank.

My question is on the physics of how this works. I know something similar is done all the time with saltwater tank and sometime freshwater, so it's possible.

If the power goes out, won't the siphon continue and just overflow the refugium until your main tank is below the hose making a huge mess?

To fix this I could put the intake very near the top of the water so it couldn't flow to much but now I would worry too much water would pump back to main tank overflowing that.

What am I missing here?


its called Aquaponics here is a video I have seen. I'm sure there are a lot more. I get the just of it but not the one to explain it to someone

ok basically the tank overflows then the pump sends it back. if the pump fails the overflow will stop.



I have, and do, use aquaponics to grow many types of vegatables. Problem with aquaponics is that you need a good amount of nutrients, aka high levels of nitrate mostly, in your water which harm most aquarium fish which are not used to conditions like that. Making a refugium using only aquatic plants would be more practical.


You use a overflow box on your main tank. Then put a siphon break in that. This way you will not have a flood if you have a power failure.

If your 29 gallon is planted, I'm thinking along the same lines as RogueAgent. I'm not sure you will have enough nutrients to support anything in a fuge. Or at least, not many. You can always dose dry ferts though. Use the EI method and adjust to having lots of plants, and I think it will work.


I'll be interested to see what happens! Good luck!


I want to build my own plant bed next to my 29 gallon planted tank.

If it's NEXT to the tank, rather than under or over it, just build the support for it up so that the desired water level in your plant bed is level with the water level in your 29.

The siphon will only even out the water level from one container to the other. The pump is always trying to push water in one direction; the siphon evens it out.

The only hazard here is if the siphon breaks. Having two or three siphon tubes, each large enough to keep up with the pump by itself, would be good insurance.

Running an airline, protected by a check valve, from the top of a siphon to the venturI intake on a good powerhead is supposed to suck air out of a siphon and keep it from breaking. I haven't tried this, so more research might be required.

Sounds like an awesome project!


I like those aquaponics video but I don't think it is exactly what I want. I want to focus on the tank, I don't really care about the well being of the plants in the fuge. I might decide to just make it under the tank and buy a cheap light for it.

I am considering something closer to this.

But what he does inside HOB filters, I would do in the sump. The plants growth, in the fuge, would be secondary. Being able to stock the most fish possible and less water changes would be my main goal.

I'm also consider buying

I would do the same sort of thing I said in the first post. It would look closer to what the guy in the video I posted show. I'm not looking to grow some outstanding houseplants which seems to be the goal of aquaponics. I'm looking to do less water changes.


Good morning,

Please keep in mind that nothing beats fresh water for your fish, refugium or not. Adding a refugium should not replace your water changes. There are nutrients in the water that the fish need that dissipate over time and they need to be replenished.

Perhaps a Hang On Back (HOB) type refugium might be something you want to look into:

Great video in the link below:

Small HOB refugium:

Ones I have, medium size:

DIY Refugium:



Thanks for the links Ken. I will check them out later today. I am not trying to do no water changes but right now I do 50% twice a week on a 29 and a 50 gallon tank. I'd like to do only 30% once a week.


Personally I think 30% once/week is reasonable, provided your tank isn't overstocked and that you observe the fish to make sure they are in good condition. As stated, however, a refugium (or algal turf scrubber, and other similar "plant filters") is not a substitute for water changes. It's really meant to compliment an aquarium, and while it will help uptake nitrates, emergent plants also need minerals in the water it sits.

That being said, in my little experience with ripariums and paludariums & aquaponics, I highly recommend you find a way to place the refugium higher than the aquarium in question. That way you can arrange an overflow system that is more reliable. Have you thought of placing a slightly smaller refugium on TOP of the aquarium? I saw this once the it's very nice, but you have to make it sturdy.

Good luck! can't wait to see how it turns out.


Personally I think 30% once/week is reasonable, provided your tank isn't overstocked and that you observe the fish to make sure they are in good condition. As stated, however, a refugium (or algal turf scrubber, and other similar "plant filters") is not a substitute for water changes. It's really meant to compliment an aquarium, and while it will help uptake nitrates, emergent plants also need minerals in the water it sits.

That being said, in my little experience with ripariums and paludariums & aquaponics, I highly recommend you find a way to place the refugium higher than the aquarium in question. That way you can arrange an overflow system that is more reliable. Have you thought of placing a slightly smaller refugium on TOP of the aquarium? I saw this once the it's very nice, but you have to make it sturdy.

Good luck! can't wait to see how it turns out.

My tank are overstocked and that is what I want. The fish in both tanks get along great, one full of Mbuna Cichlid, the other one is peaceful community fish. I know some people say fish still need more room and such but my fish seem happy and I like the look of a full aquarium. My 10 gallon in a normal stock though and I still do 50% water changes only once a week just because 5 gallons is an easy change. I do 50% twice a week on other tanks because otherwise my nitrates go above or close to 40 which I don't like.

The refugium over the aquarium is something I've toyed with in my head. I would opt to not attach it to the wall in this case. My idea is to build a stand slightly larger than my tank stand and have it go about a foot, maybe more, above it. I could drill a hole in the side near the top as an "overflow" as I'm learning it's called and of course a pump with a small tube going up to the fuge.

Only issue I see here is maintenance. It could become very much a pain for me to do water changes or service the filter and things like that. I've also considered doing it above and to the side. I suppose I could just go buy a large dresser or other tall storage furniture to place a 5-10 gallon fuge on top of.

If I go with one below. How much would just the overflow box and other things required cost? What exactly am I looking for? I already have a pump and I know I need to buy tubing and a tank or make something as the fuge.


Oh ok, so you overstock to get a certain visual effect.

Do you really want to have a refugium, or might an algae scrubber be more practical? Just a thought...

Here's a link to a bubble-up version. Of course it's possible to build your own as well, as this one is a little small. Google "algal turf scrubber" to get an idea.

Aside from that, if you're building it beside the tank, I unfortunately have no experience with that. I DO know that it will be too heavy to bolt to the wall, that's for sure. The idea of the aquarium under a stand that holds the refugium is great. It possibly could be on wheels so you can take it out for maintenance.

Aquarist48's "aquacave" links are awesome and will save you a lot of trouble if you use these are a refugium instead of having a separate tank.

I am a lazy aquarist, so personally the easiest solution is that one I tend to stick to. You might not agree.


Ok so I might just end up doing it on the top of my aquaclear 110 as a test, I will put up some pictures when I do this.

2 Questions

What is the best material to attach some plants to if I use semi-aquatic plants? (I was thinking eggcrate but want some other suggestions)

If I go with aquatic/floating plants and a clip on light, what plant would you recommend to soak up the nitrates?




+1 to hornwort. I was also going to suggest duckweed, but this floating plant will probably escape in a high current and clog things up. If you can find a way to keep them in the aquarium without the fish eating them (there are floating "nets" that one can use for this), then they multiply very quickly and take up lots of nitrates-- especially if your lighting is very bright.

Since the aquaclear 110 will be a smaller representation of what you really want to do later on, there's a possibility that you won't be able to fit both aquatic and emergent (semI - aquatic) plants in the same limited space. With a larger version down the road, either with a full refugium tank or a larger HOB refugium there will be more options. Maybe some others with more experience can chime in on this, but I would probably recommend only using emergent plants. The riparium links will help with plant selection.

A friend of mine who is really into aquaponics once did something similar with an HOB aquaclear filter. I don't know all the details, but I know that he used terra cotta "pebbles" (sold at most hydroponic stores) as an artificial soil, and planted the plants directly in it. The only problem I would see with this is that I imagine plants would need more nutrients (he might have been dosing the system with fertilizer-- I'm not sure).

There is also something for aquarium plants called "aquadurt" that apparently is very good. Could someone else on the forum give details about that? I've only heard stuff, no direct experience.

You will of course probably have to slow down the flow of the aquaclear of that size-- another link mentioned in this thread suggests changing the impeller for a smaller model's, if you have an aquaclear 50 or 20 laying around somewhere.

This is really exciting. I'm hoping to try out something similar!


Cool, hornwort is exactly what I was thinking. I have some floating around in my Mbuna tank already, and I can get a large amount for 5 bucks at my lfs. Water wisteria, I've seen used a lot but I never see it at the fish store.


I found this on ebay if you might be interested. Mind you, the light that's included wouldn't be strong enough for plants if I read it correctly, but it might be if you just plan to grow algae. Or maybe I'll try that.

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