Wet/Dry pump issues

[legendaryfrog]

Hi everybody!

i have officially started building my diy wet/dry today and i have aquestion:

how large of a pump is needed for filtering a 150 gallon goldfish tank filled with 8 medium goldfish?


The LFS recommended 500 GPH, if, i use lots of biomedia, which of course i will, now that i purchased 20 packs of potscrubbers.

 

[legendaryfrog]

Should i go with a bigger pump? or is 500 GPH fine?

 

[Rallysman]

500 gph will do the trick if that is taking into consideration the loss of flow due to head pressure.
in other words, 500 gph at the tank rather than at the pump.

someone might come in saying that more is better, but on all of my tanks with wet/drys I only turn the tank over 3x per hour and it keeps the ammonia and nitrite at 0. I have some pretty heavy stocking levels too. The only thing a higher turn over rate will do is slightly increase mechanical filtration.

 

[legendaryfrog]

what do you mean "at the tank, rather than the pump"

i planned an overflow a the intake

then once its filtered, it would be pumped back into the tank, right?

 

[Rallysman]

Right. What I'm saying is that your actual GPH will decrease more the higher it has to push the water.

For instance, if your pump is rated for 500gph, it might only actually pump 300 gph in to the tank due to the force of having to lift the water (head pressure)

I'll guess that your tank is about 5' tall, so you'll need to find something that pumps around 500gph @ 5 ft of head.
If you get a pump that's rated for 500gph @ 0ft of head, it will deliver less than that into the tank.

Here is an excellent write up on this issue. Maybe it will make more sense (I'm a crappy teacher lol)
http://www.monsterfishkeepers.com/forums/showthread.php?t=47105