Someone help me with my math

[fishfreek]

Ok. I need help as the way I am calculating this I am getting a result I just can not get with the pump that I have.

Ok. I did a water change tonight on my 80. I usually just pull one of the drain lines from the overflow out and put it in a bucket to remove water from the system. Well tonight I figured if I took both drain lines out and then counted the seconds it took to fill the bucket I could estimate the flow produced by the pump.

So I did just that and I counted in my head. (u know 1 one thousand, 2 one thousand ....) and it took approx 10sec to fill this bucket.

So, I took this time of 10 Sec and multiplied it by 6 to get the GPM flow rate. Well 5 * 6 = 30 Gal. So then i took the 30 Gal and multipied it by 60 as there are 60 min in an hour. So 30 * 60 = 1800GPH. And that result just cant be possible as the pump is supposed to put out only 1300 GPH or so at 3' of head and I got 4' of head and a few 90's in the plumbing so that should slow it down also.

So is my logic messed up someplace? I mean I am theorizing that the water comming out of the drain lines is draining as the same rate the pump is putting water into the tank. I mean its alot easier to belive a value of 1/2 of what I got at 900GPH vs the 1800GPH result that I got. But for that to have happend I would have had to count 1 sec ever 2 sec and I dont think I really counted that slow.

 

[reefrunner69]

Hmmm, My math must need some work too...

Instead of measuring that way, try filling the bucket with the return lne at the specified head, and time it with a watch...

Verify your count Have your wife put a clock on you and count the exact same way you did for the drain. See if you did count that slow...

Verify the amount in the bucket. Remember small numbers are exaggerated greatly over the course of that hour. Not really the same, but it will give you an idea of what I mean...In shooting, if your sights are off 1/16th of an inch at 7 yards, you will be off target by approx. 16" at 25yards...Bad example, but it gives you the gist of my thinking...

 

[fishfreek]

Ok. The the world is not going to implode!!!

I was counting slow. I remembered I had a stop watch on my phone so I started the stop watch and when it hit 10sec I put the lines in the bucket. Filled the bucket up to approx 5 gal mark and looked at phone and it read 25 sec so it was acutally taking me 15 sec to fill the bucket.

So with the above math that gives me a flow rate of 1200GPH. This is a belivable number as this is what I had est I would have in the tank in the first place.

I wish I could do it with the supply lines but all the lines are glued cept for the elbow going into the tank and ther is no way I can get that out of the tank without a serious mess.