Cichlids by Sanderling

Removing Surface Films From Fish Tanks

// November 1st, 2009 // No Comments » // Filtration, Fish Room Projects

12 hour acumulation of surface film

One of the benefits of having powerful bio-filtration system, is having the option of increasing loading densities and increasing feed rates without risk of high ammonia or nitrite levels as a result. The down side of doing this however is the accumulation of a thin film of lipo-protein and fish oils from that does not get digested by the biofilter because, being lighter than water it is unable to get to the sump. The image above shows the accumulation after 12 hours.

Its considered good practice to remove water from the bottom  of a tank as this tends to be the area of lowest oxygen concentration. The original drain design includes a spool piece that extends to the bottom of the tank and a strainer to keep young fish out of the sump. By adding a horizontal perforated piece and extending the strainer out to the center of the tank, the drain assembly also acts as a surface strainer. Below is an image of the new assembly;

New drain assembly

 A mesh bag keeps smaller fish from a roller coaster ride to the sump and the return pump impellor;

Here is some video of a trial using a prototype. The extension of the horizontal piece towarrds the center of the tank effectively divides the surface of the tank in two. The film is pushed into a gyre that rotates across the front edge of the skimmer and is gradually reduced. See the videos below;

Lids were recently placed on the tanks now that the cooler weather is here in order to reduce heat and moisture loss. This has the disadvantage of reducing the amount of oxygen that can diffuse into the water at the surface. To compensate, sponge filters were added to provide some makeup air above the surface of the tank and ensure that sufficient oxygen levels a e maintained. By careful placement at the center of the gyre, the film is pushed to the outside and and against the skimmer, facilitating its constant and rapid removal;

Turning Sump Design on It’s Head

// October 10th, 2009 // No Comments » // Filtration, Fish Room Projects

I’ve always been a cannister and HOB filtration kind of guy. I also like sponge filters but in spite of more than twenty active years in the hobby I’ve never had a sump. I guess I’d rather use any container big enough to be a sump to keep fish!

All good ideas have their moment however and it was simply a matter of time until I needed the bio-filtration power that only a sump with wet/dry flow capability can offer.

I recently put together a fry growing module for three species of Aulonocara in my fish room. The setup was simple enough; three 110 gallon stock tanks arranged in series filtered by a Fluval FX-5. Rated at 600 plus, gallons per hour, I figured the filter could handle the bio load no problem. As the population of juveniles and sub adult Peacocks approached 500 or so, I realized that with the amount of food I was using, I needed more filtration power than my original setup could provide.

I found a powerful submersible pump rated at 3000 gph. By running the tanks in parallel rather than in series, and collecting the discharge in a sump through separate drains, I could have ten turns per hour in each tank-plenty of filtration!

My fish room is located in the unfinished corner of the basement of our house, usually known as the furnace room. This is only the real estate that my wife has allowed me, unencumbered, to indulge in my hobby. It has become very crowded and finding room for a traditional sump design big enough for a 330 gallon system would be difficult. In fact I only had an area 2 ft square to work with,  squeezed in between my water heater and my new system.

I decided the only logical approach would be to build a stacked system; a bio-tower above a sump, with a return manifold fed from the 3000 gph submersible pump, located in the sump.

I settled upon a 50 gallon sewage basin as my sump. If your considering using one keep in mind they are pricey but there is lttle chance you’ll be tempted to use it as a fish tank and scrap your sump project. They also have the added advantage of having a 4” hub for a drain and a 3″ threaded opening that can bushed to any size you want. There is also a 2″ schedule 40 pipe clearance hole for the discharge line, a removable bolt down access cover, and a bung hole for heater and pump power cords. All in all it is a very neat package, ideal for the application. I got mine at Home Depot for $145 but you may be able to do better at a plumbing supply house.

For those who like to skip to the end to see how the project turned out, I’ve attached a picture of the (nearly) finished product. 

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