How to figure turn over rate of tank water

[EMS503]

I need to figure out what my water turn over rate is for my tank. 75 gal. reef with 20 gal. sump. I am guessing approx. 60 gals. of water between the two, allowing for the DSB & LR. My pump is rated for 1140 gph using 1" pvc. My setup is 3/4" pvc (with a run of about 2.5 feet) reduced to 1/2" pvc (with a run of about 1.5 feet) at the over flow setup. the return is gravity fed using 3/4" pvc straight to the sump. Need to know this trying to adjust flow for clam problem.
Thanks John

 

[loganj]

I'll try to figure it for you as close as possible today. I have a book that gives the equations for that. Can you tell me exactly what the piping from the pump to the tank is? How many elbows, 45*'s, ect... What kind of pump? Quiet 1?

 

[EMS503]

Thanks, The pump is a Life Guard Quite one rated for 1140 gph.(using 1" pvc wide open)
From the pump to the bottom of the overflow is 3/4" pvc with two 45's and two unions, and reducers , in the over flow 1/2" pvc with one 45 connected to an adjustable spray tube ( the kind with links that spreads out at the end.)

The first run out of the pump is 12" (upwards) to a 45 The 2nd run is 33" with two unions and a 45 at the end across the top of the cabinet (all of this is 3/4"), the third run is up to the bottom of the overflow is 9" and reduces down to 1/2"

The pvc in the overflow itself is 1/2" 18" with a 45 and out to the spray tube.

Thanks Logan, I can patch people up but really poor with math

 

[fishfreek]

This is how I calculated flow on my tank.

I took a known volume, lets say a 5 gal bucket with a line at the 5 gal mark. I measured how long it took for my overflow drain line to fill the bucket to that level.

Lets say it took 10sec.

So you figured how many 10sec intevals are in 1 min. Since this is an illistration its easy as its 10sec goes into 1min 6X. So you multiply 5gal X 6 = 30GPM. Multiply this by 60 to get GPH. THus to fill a 5 gal capacity in 10 sec that would equate to 1800GPH.

Lets say it took 30 sec to fill a 5 gal capacity. That would be 10Gal per Min and 600GPH flow.

 

[loganj]

That would be the easiest way to determine the total flow. Is that all you wanted to know? I'll figure it with what I have and see what it comes up to...may take me a while though...no math wizard here either 8O .

 

[loganj]

OK, here it is. According to what I figured, after factoring in the frictional losses in the pipe and fittings, and assuming a 1' depth in the sump, your pump is pushing against a 7'9" head. According to the flow rate charts I was able to find on your pump...probably about 475 gph. If that is correct, 99.9% of the water in the tank will circulate through the sump (total turnover) every 1:50. No guarantees on this as I haven't done enough of them to be confident that the numbers are exact, but I'm betting it's close. Reference: "Aquatic Systems Engineering" by P. R. Escobal.

 

[EMS503]

Logan & Fishfreek Thanks alot for the quick reply. I have already slowed my flow down and am seeing much better results with my clams. Im sure they thankyou to.

John

 

[fishfreek]

John, was locan correct with his calculations? Did you try my method? What flow did you have before your adjustments.

On a side note I would recomend the book Giant Clams. I am reading it now and its very informative.

 

[EMS503]

Being the fourth I had Firework detail with the Fire Dept. and didn't have the time to check it your way. But I am interested to see how close the two come. I will let you and Logan know when I do this.
I have read the book Giant clams and also found it very informative. I also keep it close by for any questions I might have before posting. This book is strongly urged to be read by Barry from Clams Direct before purchasing any clams.
Again thanks for the help as I had lost two Maxima's this last month. Possibly due to my flow rate being to fast for them.

 

[fishfreek]

One thing I found interesting was that within the book it suggested that clams kept in a nirate poor enviorment could fair worse than clams kept in an enviorment with some 'managable' level of nitrates.