A (probably dumb) question about pumps

[Lark]

I'm a bit new to all this, so I apologize in advance for a few novice questions. (I've looked in my Shimek, Fenner, and Paletta books and have not really seen the answers, so that's where you all come in.)

The main question is, how do you calculate likely needed flow rate on your return pump? In other words, are there general formulas or something for figuring out your expected overflow rate? (It looks like I'll be purchasing a tank with a built in overflow box and a 1.5 inch bulkhead fitting.) And then as a secondary question, is the goal to try to match the return rate exactly to the overflow rate and run the pump at full throtle, or do most people buy a little "more" pump than they expect to need and throtle it down? (Might that not add heat?)

Sorry, but a few more questions: Do you adjust your needed-return-flow calculations based at all on the flow rate of an in-sump pump? For example, if I run an in sump skimmer with a mag 7 does that in any way affect what I need as far as a return pump? (Can't see that it would, but I'm not among the engineering inclined.) Finally, for those of you with built in overflows in your tanks, do you put anything in there to keep the noise down? (I probably won't be using biobals.)

Thanks very much in advance.

Larry

 

[skylsdale]

Don't feel dumb...I have no clue, either.

 

[tomheo]

Hey Larry,

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote

<STRONG>The main question is, how do you calculate likely needed flow rate on your return pump? In other words, are there general formulas or something for figuring out your expected overflow rate? (It looks like I'll be purchasing a tank with a built in overflow box and a 1.5 inch bulkhead fitting.) And then as a secondary question, is the goal to try to match the return rate exactly to the overflow rate and run the pump at full throtle, or do most people buy a little "more" pump than they expect to need and throtle it down? (Might that not add heat?)</STRONG>

I had the same quesions when I first setup my tank. The thing with a built-in overflow box is that the water has to get over the gate (the top of the overflow box) to get down to the sump. So, if there's no water coming into the tank to make the water level rise to the top of the box, no water goes down to the sump. So, that means that the rate of the water that's leaving the tank is the same as the rate of the water entering the tank. Hence, as long as you don't get some crazy-big pump, you won't overflow your tank. I've got a 120g with a 1.5" hole and I was pumping back about 1600 gph (and hence draining 1600 gph) and it handled it with no problems. It looks like it could handle two-times that volume of water, too! I guess just figure out how much circulation you want in your tank. I had two holes drilled into the top of my tank (I've got a frameless tank with perimeter bracing so) to accomodate a couple of sea-swirls. The recommended cirulation ranges from 6-12 times the volume of your tank, but I had a bit more since I'm keeping SPS.

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR><STRONG>Sorry, but a few more questions: Do you adjust your needed-return-flow calculations based at all on the flow rate of an in-sump pump? For example, if I run an in sump skimmer with a mag 7 does that in any way affect what I need as far as a return pump? (Can't see that it would, but I'm not among the engineering inclined.) Finally, for those of you with built in overflows in your tanks, do you put anything in there to keep the noise down? (I probably won't be using biobals.)

Thanks very much in advance.

Larry</STRONG><HR></BLOCKQUOTE>


Your skimmer pump won't play into the equation (except maybe for noise level and electric bill). I used that Durso pipe mod thingy (I think the URL is www.rrl180.com) but the Ken Stockman version of it (the original Durso one didn't fit inside my 6"x9" overflow box). It's a significant improvement over not having it.

Hope this helps, and good luck with it!

Thomas

 

[srbayless]

Howdy,

Generally you want to find out the max gph that the overflow can handle and purchase a pump based on that figure.

Now, assuming you just have a straight run from the pump to the tank, you get a pump that has a rated GPH slightly higher than what the overflow can handle. Also, when figuring which pump has the GPH you need, don't forget to factor in the amount of head pressure you will have, usually measured in feet.

Say you have 6' of 1" hose from your pump to the end of the line in your tank. That is considered 6' of head pressure. Using smaller tubing usually reduces the GPH versus 1' tubing.

Okay, this can get complicated if you want to run multiple lines back to the tank, say using a T-fitting to have 2 returns back into the tank. As I recall, a T-fitting adds at least 1' of head pressure. You might also want to run a UV filter off of the main line, which will also reduce the GPH back to the tank.

So, as you can see it can get fairly difficult to figure out the GPH you will need. I personally just find out what the overflow can handle, and buy a pump that has at least 50% more GPH at the given feet of head pressure.

Say your overflow can handle 1000gph and you will have 6' of 1" tubing, which for most purposes means 6 feet of head pressure. I would get a pump that has 1500gph at 6' of head pressure and then restrict the flow coming out of the pump with a gate or ball valve.

I always buy equipment that is larger than what I need becuase eventually I will be upgrading to a larger tank and need the larger pump.

The insump pump running a skimmer will have no effect on your overall GPH for the system. It is basically a closed system.

Hope that helps more than confuses,

Scott.

 

[Nostrathomas]

Tomheo,Who is the maker of your tank?I am looking into purchasing one.I am in L.A.also

 

[Lark]

Thomas and Scott - thank you very much. Good info. It all makes sense. Once it's explained, that is.

 

[Rick]

Scott ,Thomas ,
I have a (dual) 1200 gph overflow box and the pump I'm going to use for it is rated at 1200 at 5 ft.head .there will be a T for the 2 returns .If I don't have enough pump power can I add a ball valve to one of the drain pipes to slow the drain .both U tubes share the same box .
I'm starting this project this week so your help on this would be great.
thanks

[ July 09, 2001: Message edited by: RJ ]

 

[tomheo]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Nostrathomas:
<STRONG>Tomheo,Who is the maker of your tank?I am looking into purchasing one.I am in L.A.also</STRONG><HR></BLOCKQUOTE>

Hey Nostrathomas,

My tank and stand are made by Lee-Mar. It's a 120g "Euro", which means that it's got the black silicon, floating bottom, no frame, perimeter bracing, and polished glass. It looks like acrylic (no greenish tinge like on normal glass tanks), and I chose to have the back painted black (included in the price). They include 2 holes in the price so I chose one hole for the overflow and 1 for a sea-swirl. I paid $12 for them to drill another hole in the top of the tank (for the other sea-swirl).

I bought mine at Aquarium City in Topanga (www.theaquariumcity.com). No, I don't work for them.

Speak to Dustin, he's really knowledgeable about the tanks and I bought it there cuz they were the cheapest by at least $30 over any other store I checked in L.A. (plus they were the only ones who knew a lot about the tanks). I paid about $690 for the tank (including the extra hole and the overflow box) and I think around $360 for the stand, but that was middle of last year, so the prices may be different. It took 'em about 3 weeks to build. If you get it, take 3 strong friends with you...that thing is HEAVY!

If you have any other questions about the tank, feel free to e-mail me!

Thomas

[ July 10, 2001: Message edited by: tomheo ]