Considering a Large Fluidized Sandbed Filter for Additional Biological Filtration.

It has been a while since the last update to my aquarium and things have started to go really well. Unfortunately most of my time has been devoted into settling into a new job but I have managed to keep up with my aquarium maintenance and I have even added a few fish. Unfortunately, most will agree that I have overstocked just a bit which has affected my water quality and aquarium in a few ways but not too drastically that it cannot be resolved with a little engineering and a few more pieces of equipment. Prior to me adding two fish about 5 weeks ago and then another 3 about 3 weeks ago my water quality was impeccable. My biological filtration was more than capable of handling the bio load as was reflected n my water parameter test and my sandbed was immaculate not showing a single sign of discoloration from algae even with a 12 to 13 hour photoperiod. But with the additional 3 fish added for a total of 5 fish the obvious happened. My bio load increased and nitrates increased from undetectable to 5.0 PPM. However, as the biological filtration in my aquarium adjust over the past few weeks the latest test from last week shows my nitrates slowly dropping and are currently at 2.5 PPM (not including this mornings test which I haven't completed). However, my sandbed is showing sign of brown algae as well as some small pockets of cyano and I am not please with that (even though its my own fault again). So I want to integrate a large fluidized sandbed filter in my aquarium to take my biological filtration of the top again.

So I am going to be purchasing the largest media reactor that I can find that doesn't dwarf my aquarium and look like an eyesore, as it is going to be placed in plain site to the left of my aquarium. For this I will be going with an Avast Marine MR16 Media Reactor that has an overall height of 17.5 inches and a footprint of 9 inches x 9 inches. This will hold approximately 24 cups of media and will be powered by an Ehiem 1260 pump as I need to have everything plumbed externally as not to crowd the aquarium with unsightly equipment. I will be utilizing Carib-Sea Arag-Alive Oolite Sand as the media. Although I understand I will have to refill this over time which means additional monitoring of the aquarium, I still believe it is a better choice than using silica based sand which will not break down and have to be replaced but theoretically can feed diatoms. Now I understand that this is a great for converting Ammonia into Nitrite and Nitrate into Nitrate which I have no issues currently but in theory if the unit was tall enough the oxygen rich water on the bottom half of the filter should get used up by the bacteria converting it to nitrates and the upper half should be able to provide an anaerobic area for the nitrate to be converted to nitrogen. If this is the case it will be a trial and error setup because I cannot place an extremely tall filter in that area but I can simulate height by daisy chaining additional fluidized sand bed filters together for the same result. Now one of the most important design aspects of implementing this is that I cannot allow a power outage to stop the water flow within the reactors for more than a few hours to prevent a tank crash due to fowled water from the bacteria smothering itself to death. So I will be employing an additional stand alone APC Batter Backups that should give me about 24 hours or more of runtime in the event of a power outage. Who knows I might even tee to feed pumps together with check valves to reduce any single points of failure. Any thoughts?

 

In my opinion, you can get better results, have a safer filter and save money if you pump water over a deep bed of sand rather than pumping it through one. In order to fully de-oxygenate a sand bed that is having water pumped through it, the flow rate will need to be incredibly slow. I tried this method in the past, and it just doesn't seem to have the turn-over rate to be a truly powerful solution. Instead what you could do it get a water storage container that will fit your space, fill it nearly to the top with sand and plumb entry and exit lines above the sand level. This way, you don't have to depend on your flow rate adjustments for keeping the parameters withing the sand bed safe for the proper type of bacteria.