Filter Placement

[kcharley]

Hi all.

In my son's 20 gal - 30 x 12 x 12 (inches) aquarium I have a HOB filter claiming 200 gal. per hour flow. I don't know how much the HOB really flows but it creates quite a current in the right third of the tank.

In an attempt to spread the flow more evenly, I moved it to the far right and piped the intake to the far left by the heater. As I suspected the additional piping has reduced the flow of the filter. It is probably still adequate for the tank but my son doesn't like the look (even though I buried the horizontal pipe in the gravel) and I am concerned about straining the filter motor.

So my current plan is to leave the filter at the far right, undo the piping and move the heater next to the intake. My concern is to spread the flow throughout the tank and keep the water temperature uniform.

Am I being too anal about a uniform temperature and current throughout the tank? The temperature variance was only 1 degree before the change. I'll be surprised if I have a 2 degree variance with my proposed setup.

Thanks in advance for any help.

 

[waterdrop]

My take/feeling on your situation is that any of the filter placement scenerios you've talked about are well within the variance of practice in the hobby. Nicely functioning tanks are described with both lower and higher flow than the average 5x turnover often recommended and which matches what your manufacturer is claiming. There are those that use 10x turnover to try and clear out all stagnant pockets in a tank the might allow ammonia/nitrate to pool and on the other end there are those that don't want even 5x flow rates to disturb off all their CO2 and blow their fish around -- and there are probably examples of both approaches that have beautiful well-functioning tanks.

You are correct that the friction of longer tubing will significantly slow the flow of a water pump as that is one of the main things it has to overcome. Considering that the 200g/h is probably optimistic, the long extensions may indeed have slowed it more than you would want.

In your case with your son's 20g, it sounds quite reasonable that you've gone back to more normal tubing and to me it seems quite reasonable not to worry about those kinds of temp variations. Fish enjoy much wider variations in their natural habitats and often fluctuation of temperature and hardness, within limits, is a positive influence on fish and is exploited by breeders. If you eventually overstock the aquarium (which I wouldn't recommend) and observe slippage in the filter's ability to hold ammonia and/or nitrite at zero or frequent need for cleaning, then you could consider another HOB for the other end of the aquarium.

~~waterdrop~~