5000 Gallon build


New Member
Thinking of doing 5000 Gallon build for Arapaima, and Alligator Gar along with some other monsters. Its going to be in a building of its own. Just wondering if anyone has any idea's on filtration and heating? Pool filters, pool heaters? Any ideas would be appreciated.


New Member
Hey Hondas thanks for the reply. I never did hear of it, but 10k is a little more than I want to drop on just the heating. I am planning on building this tank in its own building. The building will be on a concrete pad and the dimensions will be 20'x20'. The building is going to be heated by a 4000 watt OAC wall heater and be kept at a constant 80-85 degrees. Now I am thinking since the surrounding heat is at 80-85 degrees that could potentially heat the water, and use a pool filter to get the added heat. Any thoughts? The tank is already figured out. A main concern is how to keep 5000 gallons clean with very large monsters. I guess Fluval FX5's do 500 gallons each so do I run 10 FX5's? I don't know much about pool filters and technically they are not really designed for fish.


New Member
10 FX5s does not seem very realistic..
there has to be a better way to filter somthing this big i would do some more research on the filtration part of this build.


Arowana blogger
Wow, that is a big tank you are contemplating. My guess is sand filters will be your best bet. I think there are some posts somewhere on the forum with information on them? There was a forum member in Montreal HLNathan who made use of them I think.

Concerning heating, what about a dedicated hot water tank? Depending on your cost for natural gas versus electricity you might find it cheaper to go that route. You could run a loop from the aquarium to the hot water tank and then back to the tank? I am maybe thinking outside the box on this one as I am no plumber. :)

I am sure that some of the forum members in Alberta could also give you some advice, probably have to wait till the vacation season is over.


New Member
hey Brad, ya Cirrus is pointing you in the best direction with the heating, running a hot water heater tank with a heat exchanger in the sump, for filtration id run a sump just for mechanical and chemical filtration if you'd like. and FX5's couldnt do the trick, pool filters such a the Ulima II is a sand filter but they make their own bio-media made for the Ultima its pretty much the same a K1 media and they back wash for very easy maintance, they have all sizes and are mainly used for koi ponds. check out their website!!


You can forget about using 10 FX 5's, that's just ridiculous.

I use a sand filter + pool pump + sump (for extra biological filtration) for filtering my 1200 gal. ray pond. The water passes through a small pool heater, works like a dream for me. I suggest investing in the electrical and insulation of this room, it will save you $$ in the long run. I find in the summer time, you can kill the power to the heater and still keep an ambient room temp close to 90 degrees.

Another thing you need to consider is dehumidifier. You'd be amazed the rate of evaporation in a room like this. although with arapaima you will need a tank cover, which should reduce some evaporation.


For a tank that size with those fish in it and their oxygen requirements. Not to mention bio-load..

A bakki shower... or a fluidized bed...

Both are fantastic styles of filtration, and in my opinion, the 2 best.

Not to mention, both are very simple to build and highly cost effective.

For heating..... heat the room. From the sounds of it, you will be doing just that.


You may want to look at a rolling drum filter for mechanical and then a bio reactor for biological. Pool filters are good and easy but the pumps will take up alot more electricity than the ones you would use the other way. Also what will you be adding for water supply and drainage? With a tank this big you will want both of these ran to your new building. I would look at something like a hi e dehumidifier in this building also instead of the cheapy ones as it will pay for itself within a year and a half. I'm sure you will have alot more questions as this progresses. I've looked at doing this allready so I do have alot of ideas that may help along the way


New Member
I just did a quick google search Theo on the sand filter. I actually seen a similar large tank like I am planning on setting up, and I am pretty sure it was a sand filter the guy had running on it.

Joey I particularly like the Bakki Shower. I have never heard of such a filtration system. It looks fairly easy to build and effective for filtering. As you mentioned I figure that if I heat the room to 80-85 degree's that should heat the water.

Bcarlos A dehumidifier will be key I could just imagine the humidity. The top will have a large fish net attached so there will be a ton of evaporation.

I will research the ulima II as you suggested Mark.

Skynoch the rolling drum looks like a very effective method of filtration but will have to consider the costs and the space that a filter like this will take.

Thank you everyone for all your input I have some really great ideas.


New Member
+1 for the moving bed filter :) such easy maintenance and very effective
+1 for heating the room instead of the aquarium because 5000g of water will likely heat the room anyways.