chris_pull
Active Member
I want to preface this with a disclaimer that I am a novice reefer, with under a year's worth of experience and learning all the time. That said, I've wanted to post a build thread for a while as I have the impression more and more people are using canister filters on small reef tanks, yet I think they can be optimised to achieve better results. I don't want this to be a sump vs canister debate, rather that this is what has worked for me and I think it could help those who are tempted to or have gone down the canister route.
I will have to come back and update this thread with photos, but I wanted to first explain my canister set up and how I have optimised it for low maintenance, low nutrient results.
Firstly, some background on my tank: I have a 20 gallon/80 litre mixed reef that's fairly heavily stocked: pair of clowns, royal gramma, yellow clown goby, neon blue goby, pistol shrimp-goby pair, ruby red dragonette, blue star leopard wrasse (will be re-homed when it grows too large!) and the usual clean up crew. Coral wise I have a mix of soft, LPS and SPS corals, as well as a rock flower anemone. It has been running about 9 months now and, beyond the intial cycle, my nitrates have never been higher than 5 ppm. I am using the Oase biomaster thermo 350 canister filter, which has a built-in but replaceable heater. I use Tropic Marin Pro reef salt and dose soda ash several times a day to maintain alk levels (so far no need to supplement anything else). I test and log all parameters on a weekly (alk, nitrates, phosphates) or monthly basis (calcium and magnesium). I also have a Seneye tucked away in the back, though I will likely stop using this once the last slide runs out as I find it's not that accurate. Here is an older photo of my tank from November – I need to take some updated ones as the corals moved around a bit since then!
To optimise my filtration, I use a skimmer inlet designed for planted tanks. This sucks in water at the bottom and the top, in the same way a weir does on a sumped tank. This is important to skim the oil film on the surface. Given it is transparent it isn't too visible and in the long term I hope will be hidden by my gorgonian.
Water that enters the inlet then travels into a pre-filter canister that houses my mechanical filtration. At the base I have two egg-crate style coarse foams for maximum surface area, followed by a medium density foam and filter floss. Finally, I have a bag of carbon for chemical filtration, which I replace monthly. Recently, I have been experimenting with adding a sheet of 200 µm nylon mesh between the medium foam and filter floss to mimic a filter sock. This does seem to be trapping a fair bit of detritus though I am not sure if it is any better than the floss alone, which also does a great job. The benefit of having this pre-filter is that I don't have to lug out my heavy canister filter, remove all the trays with biomedia to reach the sponges at the bottom (which is where they should be to prevent detritus build up in the bio media trays). Essentially this means I don't have to touch the canister filter on a regular basis – I last opened it about 5 months ago and will open it at 6 months to give it a clean.
From this pre-filter, water enters into the canister filter. As stated above, I removed all sponges from the canister to avoid having to open it up regularly and took off the tubing on the built-in pre-filter as it was not needed and likely limited flow (this is a feature specific to this filter; no need to worry about it on other brands). Every tray is filled with BioHome marine media, which is a highly porous sintered glass type media for biological filtration. I have 4kg of biomedia in total, mimicking a sump filled with live rock (indeed you could place live rock here instead). Water also passes through a compartment with the heater within the canister, meaning this piece of equipment does not need to be in the tank. Incidentally, I use an ink bird thermostat on this heater (I set the heater to 27C and the ink bird to 25.2 C), with the probe in the DT for better accuracy. I used to get a fairly large night time drop of about .5-1C when it was really cold, but the ink bird now keeps it within .3 of a degree C.
Now we come to the part I am most pleased with: once the water exits the canister it passes into a DIY algae reactor. I made this out of the same brand of pre-filter canister that I have on the inlet for the sponges, except this one is transparent. I have wrapped 2 metres of red and blue LEDs around it and can control the brightness with a set of dimmer buttons. Inside is chaeto that I harvest about every two weeks. There is a coarse sponge at the top to prevent the chaeto entering the display. It grows incredibly well and is supporting baby turbo snails that I leave there until they grow too large, as they eat the algae that build up on the inside. When I harvest the cheato I give the sides a wipe down to keep light transmission high (the build-up is not a lot but would be if I didn't clean it). The water then returns to the tank and the outlet is placed so that it feeds directly into a wavemaker, and is thus pushed out into the tank.
Importantly, the pre-filter and algae reactor chambers are "plumbed in" using double taps, allowing me to easily shut off the water and remove the canisters without needing buckets and water going everywhere. As they are so compact and light it's easy to take them to the sink for maintenance.
Maintenance wise, I perform a weekly 10% water change and clean out the sponges/replace the floss at the same time. As mentioned above, I harvest chaeto every two weeks or so and wipe down the inside of the reactor. All in all, it takes me about an hour or so a week to maintain this system (not including daily feedings). I have very little algae and my water has that "gin clear" look to it, where the fish almost seem to be floating in the air. I add Tropic Marin reef actif weekly and think this is playing a role in keeping the water so clear.
One concern I had with this system is that the turn over rate would be too low so as to be ineffective, due to all the extra connections and piping reducing flow. However, this does not seem to be the case. Before I added the algae reactor my nitrates were consistently 5ppm though I constantly had high levels of phosphates (> 0.1 ppm). I controlled them for months using GFO in the pre-filter but it just didn't work that effectively and was messy. Since adding the algae reactor, phosphates range between 0.02-0.06ppm. My nitrates have actually begun to bottom out, so I am currently experimenting with lowering the reactor photoperiod and dosing nitrates in the meantime until I find a good balance. Clearly, the reduced flow is not a problem – in fact, it may have actually improved the effectiveness of my biomedia, since the canister is now essentially a slow-flow media reactor with plenty of contact time. I should say though that the flow from the outlet is actually still significant, which I think is due to the fact I am using an oversized filter for this tank. Moreover, I don't rely on the canister for flow in the DT; I have two jebao powerheads at either end of the tank that pulse alternatively to create lots of random flow within the tank.
One of the major benefits of adding the algae reactor is being able to massively up my feeding: in the morning, I usually feed some flakes or pellets to the fish; in the evening, I add a mix of reef roids, LPS pellets, mysis, amino acids and usually another type of frozen food (krill, baby brine, rotifers etc) for the fish/corals. Since doing this I've seen great polyp extension on things like my SPS and gorgonians, and my micromussa are super fat and fluffy, usually with tentacles extended all the time now.
Although I think sumps are indeed the way to go on larger tanks, my experience so far is that canisters can be used effectively on smaller tanks and are not nitrate factories if set up properly. Although I now have an algae reactor, I ran this system without one for ~ 7 months and my nitrates have never risen above 5ppm, depsite starting with dry rock. I think where people might run into issues is not using enough biomedia and having too much sponge, which can trap a lot of detritus even when cleaned reguarly, and they are often placed at the top, meaning detritus is trapped and builds up in the bio media below it. Having the separate canister for sponges before the biomedia ensures the biomedia works effectively without being clogged and it is just much eaiser to maintain. I buy big sheets of cheap but high quality coarse and medium pond sponges that I cut to size and so can replace every 6 months or so.
I will try and update this post with more detailed photos of the set up so people using canisters can see if it would help improve their system or not. I will also try and update as my system matures and grows, so I document whether canister filters are good long term solution or not.
Thanks for reading!
I will have to come back and update this thread with photos, but I wanted to first explain my canister set up and how I have optimised it for low maintenance, low nutrient results.
Firstly, some background on my tank: I have a 20 gallon/80 litre mixed reef that's fairly heavily stocked: pair of clowns, royal gramma, yellow clown goby, neon blue goby, pistol shrimp-goby pair, ruby red dragonette, blue star leopard wrasse (will be re-homed when it grows too large!) and the usual clean up crew. Coral wise I have a mix of soft, LPS and SPS corals, as well as a rock flower anemone. It has been running about 9 months now and, beyond the intial cycle, my nitrates have never been higher than 5 ppm. I am using the Oase biomaster thermo 350 canister filter, which has a built-in but replaceable heater. I use Tropic Marin Pro reef salt and dose soda ash several times a day to maintain alk levels (so far no need to supplement anything else). I test and log all parameters on a weekly (alk, nitrates, phosphates) or monthly basis (calcium and magnesium). I also have a Seneye tucked away in the back, though I will likely stop using this once the last slide runs out as I find it's not that accurate. Here is an older photo of my tank from November – I need to take some updated ones as the corals moved around a bit since then!
To optimise my filtration, I use a skimmer inlet designed for planted tanks. This sucks in water at the bottom and the top, in the same way a weir does on a sumped tank. This is important to skim the oil film on the surface. Given it is transparent it isn't too visible and in the long term I hope will be hidden by my gorgonian.
Water that enters the inlet then travels into a pre-filter canister that houses my mechanical filtration. At the base I have two egg-crate style coarse foams for maximum surface area, followed by a medium density foam and filter floss. Finally, I have a bag of carbon for chemical filtration, which I replace monthly. Recently, I have been experimenting with adding a sheet of 200 µm nylon mesh between the medium foam and filter floss to mimic a filter sock. This does seem to be trapping a fair bit of detritus though I am not sure if it is any better than the floss alone, which also does a great job. The benefit of having this pre-filter is that I don't have to lug out my heavy canister filter, remove all the trays with biomedia to reach the sponges at the bottom (which is where they should be to prevent detritus build up in the bio media trays). Essentially this means I don't have to touch the canister filter on a regular basis – I last opened it about 5 months ago and will open it at 6 months to give it a clean.
From this pre-filter, water enters into the canister filter. As stated above, I removed all sponges from the canister to avoid having to open it up regularly and took off the tubing on the built-in pre-filter as it was not needed and likely limited flow (this is a feature specific to this filter; no need to worry about it on other brands). Every tray is filled with BioHome marine media, which is a highly porous sintered glass type media for biological filtration. I have 4kg of biomedia in total, mimicking a sump filled with live rock (indeed you could place live rock here instead). Water also passes through a compartment with the heater within the canister, meaning this piece of equipment does not need to be in the tank. Incidentally, I use an ink bird thermostat on this heater (I set the heater to 27C and the ink bird to 25.2 C), with the probe in the DT for better accuracy. I used to get a fairly large night time drop of about .5-1C when it was really cold, but the ink bird now keeps it within .3 of a degree C.
Now we come to the part I am most pleased with: once the water exits the canister it passes into a DIY algae reactor. I made this out of the same brand of pre-filter canister that I have on the inlet for the sponges, except this one is transparent. I have wrapped 2 metres of red and blue LEDs around it and can control the brightness with a set of dimmer buttons. Inside is chaeto that I harvest about every two weeks. There is a coarse sponge at the top to prevent the chaeto entering the display. It grows incredibly well and is supporting baby turbo snails that I leave there until they grow too large, as they eat the algae that build up on the inside. When I harvest the cheato I give the sides a wipe down to keep light transmission high (the build-up is not a lot but would be if I didn't clean it). The water then returns to the tank and the outlet is placed so that it feeds directly into a wavemaker, and is thus pushed out into the tank.
Importantly, the pre-filter and algae reactor chambers are "plumbed in" using double taps, allowing me to easily shut off the water and remove the canisters without needing buckets and water going everywhere. As they are so compact and light it's easy to take them to the sink for maintenance.
Maintenance wise, I perform a weekly 10% water change and clean out the sponges/replace the floss at the same time. As mentioned above, I harvest chaeto every two weeks or so and wipe down the inside of the reactor. All in all, it takes me about an hour or so a week to maintain this system (not including daily feedings). I have very little algae and my water has that "gin clear" look to it, where the fish almost seem to be floating in the air. I add Tropic Marin reef actif weekly and think this is playing a role in keeping the water so clear.
One concern I had with this system is that the turn over rate would be too low so as to be ineffective, due to all the extra connections and piping reducing flow. However, this does not seem to be the case. Before I added the algae reactor my nitrates were consistently 5ppm though I constantly had high levels of phosphates (> 0.1 ppm). I controlled them for months using GFO in the pre-filter but it just didn't work that effectively and was messy. Since adding the algae reactor, phosphates range between 0.02-0.06ppm. My nitrates have actually begun to bottom out, so I am currently experimenting with lowering the reactor photoperiod and dosing nitrates in the meantime until I find a good balance. Clearly, the reduced flow is not a problem – in fact, it may have actually improved the effectiveness of my biomedia, since the canister is now essentially a slow-flow media reactor with plenty of contact time. I should say though that the flow from the outlet is actually still significant, which I think is due to the fact I am using an oversized filter for this tank. Moreover, I don't rely on the canister for flow in the DT; I have two jebao powerheads at either end of the tank that pulse alternatively to create lots of random flow within the tank.
One of the major benefits of adding the algae reactor is being able to massively up my feeding: in the morning, I usually feed some flakes or pellets to the fish; in the evening, I add a mix of reef roids, LPS pellets, mysis, amino acids and usually another type of frozen food (krill, baby brine, rotifers etc) for the fish/corals. Since doing this I've seen great polyp extension on things like my SPS and gorgonians, and my micromussa are super fat and fluffy, usually with tentacles extended all the time now.
Although I think sumps are indeed the way to go on larger tanks, my experience so far is that canisters can be used effectively on smaller tanks and are not nitrate factories if set up properly. Although I now have an algae reactor, I ran this system without one for ~ 7 months and my nitrates have never risen above 5ppm, depsite starting with dry rock. I think where people might run into issues is not using enough biomedia and having too much sponge, which can trap a lot of detritus even when cleaned reguarly, and they are often placed at the top, meaning detritus is trapped and builds up in the bio media below it. Having the separate canister for sponges before the biomedia ensures the biomedia works effectively without being clogged and it is just much eaiser to maintain. I buy big sheets of cheap but high quality coarse and medium pond sponges that I cut to size and so can replace every 6 months or so.
I will try and update this post with more detailed photos of the set up so people using canisters can see if it would help improve their system or not. I will also try and update as my system matures and grows, so I document whether canister filters are good long term solution or not.
Thanks for reading!
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