700gph or 1500gph?

[Newt56]

So I have decided after much research to drill vs doing a HOB overflow on my 75 gallon. Going to order the entire overflow kit from Glass_holes. com and my husband is going to be the brave one who drills the tank.

My question is, should I go with the 700gph or the 1500gph for 75 gallon? I'm going to have a 29 gallon sump underneath with a either a mag drive or Eheim pump.

Another question, does the return pump have to match the 700/1500gph coming from the tank? Still very confused about what size return pump I would need.

So if I went with the 700gph overflow kit, would this MD7 pump work?
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+4587+4590&pcatid=4590

Thanks!!

 

[KafudaFish]

You want your kit's ability to be greater than your pump's rating not equal. More water being pushed usually means more energy consumption and more noise though there are ways around the sound.

With a 75 you are looking at a return rate of around 300 - 375 gph since most run 4 to 5 times your display volume through the sump. A mag 7, 9 or 12 or Eheim 1260 or 1262 would all work. If you still have too much pump you can T the return line and direct the flow somewhere else like a fuge or a reactor to drive bio pellets or carbon vs. having another plug.

One thing to remember is when you have a 45 or a 90 elbow on the pvc the flow rate slows down so if you have several due to the stand that kit maybe able to handle 500 gph instead of the 700.


Mags are usually work horses but most people don't like them due to noise levels (if this is important) and energy consumption. Eheims are work horses too and there are a few other return pumps that are as quiet or more so such as the water blaster, the smaller sicce or the tunze for example.

 

[thegrun]

I like to go with a little more flow through my sump, 6-9 times the DT so for you 450-675 GPH which is getting close to the 700 GPH rating on the smaller overflow. The short answer is if you don't mind the extra space the 1500 takes up, I would go with the larger overflow for a safety margin. Your pump can be smaller than rated capacity. You are not going to actually get the rated flow of the pump because of head pressure loss (the vertical distance the pump has to push the water to get it from the sump back up to your DT). There are charts here on RC or available from most pump manufacturers that will tell you how much water the pump will actually deliver to your DT. I used Mag pumps for many years, they are reliable but do tend to make more noise and use more energy than Eheim pumps. I've been using Eheim pumps for the last 5 years and they are worth the extra money to me.

 

[Palting]

First of all, the MD7 does put out 700 gph, but that's at 0 head. With a sump under the display, there is usually a 4 foot head. MD7 puts out 480 gph at 4 foot head. That should be more than enough for a 75 gallon DT with 29 gallon sump, and a 700 gph overflow.

 

[rerr001]

I have a 75G with a 30g sump and I got the gl******* 1500gph. Drilled it myself and been running it for about 3 months now. Works great. Running two 3/4" returns with a Sicce 3.0 return pump, will be upgrading to a eheim 1262 soon.

 

[GroktheCube]

I'd go for the 1500 box. A larger surface skimming area is always preferable.

I'd also recommend the Eheim pump over the MagDrive. It will be much quieter, consume less energy, and you can use smaller piping and still get good flow. The MagDrive flow rates are rated using 1.5" piping.

 

[billdogg]

My vote is for the larger overflow box as well, although the smaller one should be more than adequate for your tank. As for the return pump - You cannot go wrong with an eheim. I have a 1262 that I got used from the LfS I worked part time at. It was used in their feeder goldfish tank for many years before i got it. I took it home, cleaned it up, and put it in service. It is still going strong. I've replaced the impellor maybe once, and clean it about once a year. Oh - and I got it sometime around 1990

 

[Sokretys]

The 1500gph. Stay away from mag drives though. Sicce Syncra is the bees knees

 

[Newt56]

Thanks again for all the help!! Looks like the Sicce Syncra is better on energy consumption, which is definitely what I'm looking for.