Nursery Tank Fix

So I thought I was done with the nursery tank. But yesterday it started overflowing. And the school was locked up and no one was around. It overflowed so much that is flooded the floor and got to the power strip that was below the tank. Water got into the power strip, tripped the GFI outlet, and turned off the pump which stopped the leaking. So at least we didn't loose all our saltwater and the salinity didn't drop a lot (if water leaks out of the tank its replaced by freshwater through the autofill, so the salinity drops.) I watched this all unfold from my house and hour away through the pan and tilt webcam.
Today I went out there to fix this mess. I dried out the outlet strip and got that all working again. I then replaced the two 1" syphons with a 1.5" syphon. I also instead of using window screen at the end of the pipe I used the stuff people use to block leaves from getting into their gutters. This has a large hole size so more stuff gets through. I also cut the stand for the overflow box shorter so that whole box is lower relative to the tank.
My dad also built a screen for the top of the nursery tank so the fish don't get out. And I also did some repairs to the algae scrubber. I removed one layer of the mesh and repalced some zipties that were broken.

Nursery Tank - Finished

The Nursery Tank is finished. I went through a few redesigns as far as plumbing before I got it working properly. My father reinforced the wooden sand filter cover with some cross braces to make sure it could hold the tank.

So, the original design of having a 1" pipe with the the multiple bends didn't work. It either entirely filled up and became a long winding syphon and drained the tank too fast, or the water didn't flow over the syphon bulkhead fast enough so the water level in the tank got to high. Next I looked a commercial boxes made for this purpose and copied that design, which fetures an exterior box. This didn't go fast enough either. If you look back at the old post for this nursery tank I said that 1" would work because the nursery tank is 5" above the big tank. This is true but the syphon bulkhead is not 5" above, its 0" above. That's why it didn't flow fast enough. So I put in a second pipe to syphon the water out. I ended up with two 1" pipes syphoning the water out of the tank into the box and two 1" pipes draining the box. See the pic above.

The feed to the tank was fairly simple. Using my pond pump I got the connections to get it to PVC which went from the big tank to the nursery tank. In the nursery tank I ran the PVC horizontally along the water level and made ten 11/16" holes at various angles. Ten holes at 11/16" because that is what I calculated as the same cross sectional area as the PVC feed pipe. A few days later when I got the return working I put some sea plants in it and found that there was lots of movement in the water, just what I wanted.

I also did a back wash, the pressure of the sand filter is now down to around 12psi, it was around 22psi. I also set up the computer with a pan and tilt webcam and temperature sensors. The camera I put on a 2x4 in the back of the room. I put one temperature sensor in the tank and the other in the room. The room one is to monitor whether the air conditioner is working or not, its has to be restarted about weekly now. The computer was not connecting to the Internet which I need in order to remotely log in and get the camera. Bill took a good portion of his afternoon to help me fix the problem. It turned out that the switch was having a conflict with a wireless access point in regards to it's IP address, we ended up just putting the computer on a different switch. We also spent large amount of time looking for software for the temperature probes, which we found in Patty's lab.

This all took four days, day one cleaning and planning; day 2 was reinforcement, feed plumbing, and version one of return; day three was version 2 of return; and day four was version 3 of return and computer set up.

I also got some new fish in the tank, a bunch of silversides, a big hermit crab, some other stuff I can't identify, and this one.... in the picture.... does anyone know what this is?

Nursery Tank

I cleaned out the soon to be nursery tank today. It was at one point a coral reef tank but hasn't been maintained. This smaller tank is made out of glass and can be carried around so it wasn't difficult to clean.

I'm going to use a small pond pump that I have to get water into it and use gravity to get the water back. I needed to figure out how big of a pipe I will need in order to get the water to flow back into the big tank at the same rate that the pump is filling it up. I found a great book called Aquatic Systems Engineering: Devices and How They Function by P.R. Escobal. It is amazingly helpful in its analysis of life support systems. In this case I opened up to the section on the modified Bernoulli Equation.

I put the pump in my swimming pool and timed how long it took to fill a 5 gallon bucket. The pump flows at 339 gph. For my purposes I did not need to account for head pressure because this gravity return pipe doesn't have a pump. For this I used the following formula:

H_n= H_B + b K G²/d⁴

Where

H_n = water level in nursery tank

H_B = water level in big tank

b = constant = 7.2035x10-7

K = Friction Loss

G = GPH

d = diameter of pipe

I used the following values. K was calculated by this: There will be 6 elbows each worth of friction value of .9 that equals 5.4.

5.5 = 5 + 7.2035x10^-7 x 5.4 x 339.6²/d⁴

d is around .9 inches

Note that I gave only the hight of the nursery tank above the big tank a value of .5 ft, this is a little safe so that the drain will remove water faster than the pump will fill. Also the drain pipe is not going to be a simple U syphon, it will be designed so the water level stays constant no matter what. See the the pic below to get the idea.

No Nitrate?

I did a nitrate test today and found that the wasn't any. Which is rather strange because two weeks ago it was almost off the scale. I think that either enough algae grew and used up the nitrate, or the test kit all of the sudden went bad. Salinity is still low, pH and alkalinity is good. I set a trap off of the old Ponquogue bridge. I got a few things yesterday and hopefully I will get more later on.

I'm making plans for the summer. I need to put a net over the top of the tank to prevent fish from jumping out. I need to divide the tank so I can separate large fish from small fish. And I still have to block some of the sunlight and set up the nursery tank.