First let me say that this is not my idea. I got this idea from Nano-reef, and I've done a lot of learning at their pico section, which is great. But I believe in passing on what I've learned, so I'm sharing this information now with you.
My tank's little! Where do I put all this stuff???
One of the problems with pico reefs and nano reefs on the small end of nano, say up to 15g, is that you have a limited amount of real estate with regard to placing equipment.
You need your light, you need your power head, you need your heater... Believe me, it adds up.
Another problem with these smaller tanks is the practicality of a protein skimmer and a sump. Most protein skimmers are simply not small enough to fit in a pico, and if they do fit, it takes up a lot of tank real estate. With regard to sumps, while I've seen sumps employed successfully in picos and small end nanos, you begin to wonder what's the point of having a pico if the sump is larger? 
A nice solution for these smaller tanks is to employ a refugium. Don't get me wrong, big tanks use them too. In fact, this is usually part of the function of a sump in larger tanks. But this specific article is more designed for picos and smaller nano tanks.
What's a refugium?
A refugium is a chamber or even a small tank away from the main display tank but that shares the same water supply. It can hang onto the main tank and has it's own flow system.
It can't be accessed from the outside by predatory fish or display invertebrates, so it becomes a safe haven, a refuge if I may, for the smaller organisms in a reef aquarium. Copepods, amphipods, small starfish, and other small critters that would otherwise become food and be unable to establish a breeding population in the main tank.
Predatory animals can't get in, but these small organisms can get out, providing predatory animals with food without disturbing the breeding population
Refugiums also can be used for macro algae propogation. Nutrient export is an important part of maintaining a clean and healthy reef. Of course this can be done by chemical filtration, protein skimming, and yes, water changes, but macro algae consumes ammonia, nitrite, nitrate, and phosphate, like any other plant-like organism. It can be used a long with chemical means to keep a tank clean.
Refugiums can also store LR rubble to increase your filtering capacity. That being said, LR rubble also has many crevices that can store detrius too, so be aware that that accumulated detrius can also possibly generate nitrates. Not saying LR rubble is bad, but be judicious in it's use.
Larger Refugiums also sometimes employ a sand bed of some type, as a breeding ground for pods and other beneficial organisms. But also be warned, Deep sand beds cannot be disturbed or you'll release hydrogen sulfide gas into your display tank. For our purposes in this thread, don't worry about a Deep sand Bed or even substrate. This is beyond the scope of a modified Aquaclear filter. At least IMO.
Refugiums need a light source. Especially if you decide to grow macro algae. The most typically grown macro algae in a refugium is Chaetomorpha, or chaeto for short. It is a macro algae that sucks up nitrates and phosphates. See its care here. Other macro algae and even Mangroves can be employed in the refugium for nutrient export.
As I said, one of the problems of picos and small nano is real estate. There is simply not enough room. A great way to resolve this issue is to combine two functions into one unit. Converting an Aquaclear brand filter into a refugium takes care of a few things.
1. Creates more flow in your aquarium
2. Provides several chambers to store small pieces of equipment away from the main display tank
3. Provides a refuge for smaller organisms to breed
4. If provided with a light, it can grow chaeto for nutrient export.
5. It hangs on the back of your aquarium very easily and it's made of a durable plastic.
What's an Aquaclear filter?
Aquaclear filters are a US brand of Hang on the back external power filters manufacture by Hagen. It comes in a range of sizes, from the 20 to the 110. The best ones for refugium conversion are the 30, 50, 70, and 110, with the 70 being the most popular. Why not use just any old Hang on the back filter? Well, the Aquaclear features some construction advantages that render it particularly useful to convert to a refugium.
1. It's clear!! Making it easy to light
2. the chamber for filter media storage is huge! See, Aquaclear's media storage isn't done by a cartridge slots which is typical in a HOB filters, but by a basket. This allows for a lot of room. The 110 is practically a small tank.
3. The filters are of simple construction and can be easily modified.
4. Adjustable flow capabilities.
Converting an Aquaclear filter into a Refugium
While, the nano-reef thread lists quite a few pieces of equipment, I constructed my refugiums with the following...
1. Aquarium sealant
2. regular tape
3. A wooden stick of some type to push the sealant into the grooves, I've used just about anything... chopsticks, toothpicks, cuticle pushers, it doesn't matter
4. A good steak knife. You don't need a saw, that's just overly dramatic.
1. This is your naked aquaclear out of the packaging. I'm using an Aquaclear 30 as this was for my 4g pico. I used an Aquaclear 50 for my 8g. Many opt for the 70 or even the 110. The uptake tube is on your left, the outflow is to your right. See how big the chamber is? Take out the basket.
2. Using your knife or even good scissors, cut up your media basket until you have the following two pieces. The bottom piece is going to be sealed to the outflow, and forms a barrier so stuff can't come into the fuge and your macro can't get out. The top piece is going to form a barrier between the uptake chamber and the main media chamber so that flow isn't impeded by macro algae.
3. The pieces will eventually fit together like this.
4. To make this happen, you gotta use your knife to gauge out a notch in the piece for the outflow barrier. Like this...
You'll end up with this...
5. Now this is a 4 day job, Sealant needs time to cure.
6. Day one; do steps 1-4. And you'll need to attach your outflow barrier to the front of the media chamber. Notched side facing into the chamber. Cause you need to fit the other piece.
7. You gotta adjust it so it's high enough. Flush with the top of the media chamber is good. You can always seal any gaps with sealant.
8. Once you've placed it, check the fit of the second piece... Should look like this. See, why I made the notch?
9. Remove the second piece and use Aquarium sealant to seal the outflow barrier into place... Let it cure for a day. DON'T put it in water. Can't do that yet.
10. Day two... Take the second piece and place it in the fuge. Cut off any excess sealant.
11. Seal it in place. Let it cure for a day. Don't put it in the water yet!!!!
You can see that it creates a sort of mini chamber to the left of the main refugium chamber. You can do a bunch of things with this. I put a pico heater in.
Others put chemical media. You don't need a lot for tanks this small.
You can't do a water test until 48 hours after you use the sealant, so either you can wait or adjust your uptake tube. This is an optional step. I didn't have to do this for my 8g, but I needed to do this for my 4g's fuge.
Adjusting your uptake tube length...
1. Determine how much of the tube you have to cut. Mark it by scratching the plastic with your knife.
2. Put scotch tape around the tube so you don't damage it while you cut.
3. Cut off the section.
Day 4; Adding your light & installing the refugium.
Lighting is up to you. For my MH tank, I was actually able to grow some good chaeto just using it's ambient lighting, but I wanted faster growth, so I eventually purchased this LED fixture that I'm using as the display light in my 4g.
It has a flexible neck & it's clip on. Here's what my two refugiums look like all setup. The 8g fuge needs a bit of a clean...
Right now, I'm running my refugiums on opposite photoperiods. So when my display lights go off, the fuge lights go on. Mine are very simple setups. I've got a few pods and just the chaeto. I may add some LR rubble from the tanks so I can use my refugiums more for pod growth in addition to the nutrient export that it's currently being used for. I also may add additional media to the 8g refugium.
A note on flow - You can adjust the flow of a larger aquaclear, buy removing the original impeller and replacing it with an impeller from a smaller model. I've not needed to do this.
Putting it in perspective, or why go through all this hassle? - My aquaclear 50 refugium cost like $23 on sale and a tube of Aquarium sealant is less than $5. Your average HOB refugium is significantly more expensive, the cheapest models being about $150 or so. The options that approach this affordability are IN-TANK refugiums, again defeating the purpose of this thread which is to give you more space inside your tank in the first place.
Thanks for looking. I'll definitely leave this thread open for questions and commentary. This is a very simplified guide.
L
My tank's little! Where do I put all this stuff???
What's a refugium?
As I said, one of the problems of picos and small nano is real estate. There is simply not enough room. A great way to resolve this issue is to combine two functions into one unit. Converting an Aquaclear brand filter into a refugium takes care of a few things.
1. Creates more flow in your aquarium
2. Provides several chambers to store small pieces of equipment away from the main display tank
3. Provides a refuge for smaller organisms to breed
4. If provided with a light, it can grow chaeto for nutrient export.
5. It hangs on the back of your aquarium very easily and it's made of a durable plastic.
What's an Aquaclear filter?
Aquaclear filters are a US brand of Hang on the back external power filters manufacture by Hagen. It comes in a range of sizes, from the 20 to the 110. The best ones for refugium conversion are the 30, 50, 70, and 110, with the 70 being the most popular. Why not use just any old Hang on the back filter? Well, the Aquaclear features some construction advantages that render it particularly useful to convert to a refugium.
1. It's clear!! Making it easy to light
2. the chamber for filter media storage is huge! See, Aquaclear's media storage isn't done by a cartridge slots which is typical in a HOB filters, but by a basket. This allows for a lot of room. The 110 is practically a small tank.
3. The filters are of simple construction and can be easily modified.
4. Adjustable flow capabilities.
Converting an Aquaclear filter into a Refugium
While, the nano-reef thread lists quite a few pieces of equipment, I constructed my refugiums with the following...
1. Aquarium sealant
2. regular tape
3. A wooden stick of some type to push the sealant into the grooves, I've used just about anything... chopsticks, toothpicks, cuticle pushers, it doesn't matter
4. A good steak knife. You don't need a saw, that's just overly dramatic.
1. This is your naked aquaclear out of the packaging. I'm using an Aquaclear 30 as this was for my 4g pico. I used an Aquaclear 50 for my 8g. Many opt for the 70 or even the 110. The uptake tube is on your left, the outflow is to your right. See how big the chamber is? Take out the basket.
2. Using your knife or even good scissors, cut up your media basket until you have the following two pieces. The bottom piece is going to be sealed to the outflow, and forms a barrier so stuff can't come into the fuge and your macro can't get out. The top piece is going to form a barrier between the uptake chamber and the main media chamber so that flow isn't impeded by macro algae.
3. The pieces will eventually fit together like this.
4. To make this happen, you gotta use your knife to gauge out a notch in the piece for the outflow barrier. Like this...
You'll end up with this...
5. Now this is a 4 day job, Sealant needs time to cure.
6. Day one; do steps 1-4. And you'll need to attach your outflow barrier to the front of the media chamber. Notched side facing into the chamber. Cause you need to fit the other piece.
7. You gotta adjust it so it's high enough. Flush with the top of the media chamber is good. You can always seal any gaps with sealant.
8. Once you've placed it, check the fit of the second piece... Should look like this. See, why I made the notch?
9. Remove the second piece and use Aquarium sealant to seal the outflow barrier into place... Let it cure for a day. DON'T put it in water. Can't do that yet.
10. Day two... Take the second piece and place it in the fuge. Cut off any excess sealant.
11. Seal it in place. Let it cure for a day. Don't put it in the water yet!!!!
You can see that it creates a sort of mini chamber to the left of the main refugium chamber. You can do a bunch of things with this. I put a pico heater in.
Others put chemical media. You don't need a lot for tanks this small.
You can't do a water test until 48 hours after you use the sealant, so either you can wait or adjust your uptake tube. This is an optional step. I didn't have to do this for my 8g, but I needed to do this for my 4g's fuge.
Adjusting your uptake tube length...
1. Determine how much of the tube you have to cut. Mark it by scratching the plastic with your knife.
2. Put scotch tape around the tube so you don't damage it while you cut.
3. Cut off the section.
Day 4; Adding your light & installing the refugium.
Lighting is up to you. For my MH tank, I was actually able to grow some good chaeto just using it's ambient lighting, but I wanted faster growth, so I eventually purchased this LED fixture that I'm using as the display light in my 4g.
It has a flexible neck & it's clip on. Here's what my two refugiums look like all setup. The 8g fuge needs a bit of a clean...
Right now, I'm running my refugiums on opposite photoperiods. So when my display lights go off, the fuge lights go on. Mine are very simple setups. I've got a few pods and just the chaeto. I may add some LR rubble from the tanks so I can use my refugiums more for pod growth in addition to the nutrient export that it's currently being used for. I also may add additional media to the 8g refugium.
A note on flow - You can adjust the flow of a larger aquaclear, buy removing the original impeller and replacing it with an impeller from a smaller model. I've not needed to do this.
Putting it in perspective, or why go through all this hassle? - My aquaclear 50 refugium cost like $23 on sale and a tube of Aquarium sealant is less than $5. Your average HOB refugium is significantly more expensive, the cheapest models being about $150 or so. The options that approach this affordability are IN-TANK refugiums, again defeating the purpose of this thread which is to give you more space inside your tank in the first place.
Thanks for looking. I'll definitely leave this thread open for questions and commentary. This is a very simplified guide.
L
