Luca Brazzi
06-01-2003, 2:58 AM
In my 75 gallon drilled acrylic tank with internal overflow, I decided to build and install an undergravel jet system to create water movement in the tank (see http://www.cichlid-forum.com/articles/ug_jets.php).
This does work well for keeping things strirred up, however, as with most things there are tradeoffs. The major tradeoff that I have noticed with having an undergravel jet system is that unless you are an advanced Mathematician, well versed in the Theory of Chaos, and are able to calculate the precise jet angles and pressures, and angle the jets just right... there is no way you can have an undergravel jet system that does not adversely effect the flow of debris into your filter.
When my UGJ's are on the visible debris in the tank is constantly moving and the currents formed by the jets keep the debris from getting sucked into the overflow. When the jets are off, and things are relatively stable in the tank, the overflow can suck in debris from as far away as 15 inches.
I even rerouted the blast from the sump return jet to point straight down into the tank so as to not cause lots of current on the surface. This allows the return to be the major source of movement on the surface of the water, and anything within its reach now gets sucked in.
So... what I would add to the article above is that IMHO, the best of both worlds would be to have an Undergravel Jet system with some form of timer on it so that it would come on for 10 or 15 minutes, stir things up, then turn off and stay off for a couple of hours to let what has been stirred up get sucked into the filter.
This does work well for keeping things strirred up, however, as with most things there are tradeoffs. The major tradeoff that I have noticed with having an undergravel jet system is that unless you are an advanced Mathematician, well versed in the Theory of Chaos, and are able to calculate the precise jet angles and pressures, and angle the jets just right... there is no way you can have an undergravel jet system that does not adversely effect the flow of debris into your filter.
When my UGJ's are on the visible debris in the tank is constantly moving and the currents formed by the jets keep the debris from getting sucked into the overflow. When the jets are off, and things are relatively stable in the tank, the overflow can suck in debris from as far away as 15 inches.
I even rerouted the blast from the sump return jet to point straight down into the tank so as to not cause lots of current on the surface. This allows the return to be the major source of movement on the surface of the water, and anything within its reach now gets sucked in.
So... what I would add to the article above is that IMHO, the best of both worlds would be to have an Undergravel Jet system with some form of timer on it so that it would come on for 10 or 15 minutes, stir things up, then turn off and stay off for a couple of hours to let what has been stirred up get sucked into the filter.