[paladine28]

i ahve seen some tanks that have a pvc pipe with holes in it for there return to me it seems that this would help with water flow and eliminate dead spots if planned right my question is how big a pump would you have to have for a 90 gal tank and also i have a hang on overflo that i can't find a name on or any info but it has duel outlet hoses so it has to be moving a lot of water any ideas on how i can make this work thaks

[PDAJunkie]

You don't say if your 90 gal is a reef tank or "fish only" tank. The idea water turn over rate to strive for is 6-10 times your tank size per hour. Many aquarists feel that more is better, especially for a reef tank system. In your case with a 90 gal tank the flow rate to strive for would be 900 gph. The next question you have to ask yourself is where will the return pump be located. Location will play an important part in determining the size of pump to purchase. For example, if your return pump is located directly below your tank and is only having to pump 'up hill' a couple of feet than you can get by with a smaller pump than say myself, whose retun pump is in my basement. The 'up hill' resistence to the pump is "head pressure". So in theory (sp?) if you have a pump located 3' foot below the output level of your return piping you would look for a pump with a gph rating of at least 900gph @ 3' of head. That said, if you then looked at say a Mag12 pump, you would find that they have a rating of 1100 gph at 4' of head which would suit your needs. Hope all of that made sense. Sometimes I can be pretty winded and end up saying nothing.
The gph flow of your hang on overflow would depend on the size of your outlet hoses. I believe that most dual have a 1" outlet which would be a rating of 1200 gph for the dual outlets providing you do not reduce them going into the pump.

[Reefland]

I believe you are talking about a spray bar, and if so, they can be helpful to get water flowing throughout the tank. However, I would look at other means since the spray bar, with a powerful pump, will put a lot of power behind those small streams and that isn't necessarily a good thing.

[paladine28]

thanks guys i think i'm just going to do an over the back closed loop because i think my tank is tempered and i don't want to have to buy a new one to find out for sure with my luck if i try and drill it it will be tempered and also i'm probably going to start off fish only maybe some shrooms or softies but will eventually get up lps just have to get back into it more and learn more before i get that deep and end up killing things

[Reefland]

Those over the back closed loops aren't as easy as one might think, I have had horrible struggles trying them in the past. You might consider a nice Tunze Stream or Ecomarine Vortech.