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Comment by Bob Campbell on March 4, 2012 at 12:36am

Can anyone tell me if it is best to use plastic to cover a frame for a greenhouse or shade cloth instead? Im going to be using an evap cooler, misting system, fans and vents.

I think polyethylene will be better for your plants.  Shade cloth cuts quite a bit of light.   Checkout the high tech plastics available now. 

I had a very successful green house in Tucson near Swan and River Road back in 1985 using Polycarbonate. I placed Aspen cooler pads along the bottom of the South wall about 30" high and a 20" room fan pulled the air out near the peak of the  green house.  It was a very low tech system, but it worked well.  Heat will prohibit tomatoes from setting fruit, but most plants can take the heat as long as they get water.

I had a tomato plant that had a 3" trunk .  It went 10' to the the roof and curved back down.  It produced fruit for about three years until the soil developed nematodes.

Comment by David Schwinghamer on March 4, 2012 at 12:05am

Can anyone tell me if it is best to use plastic to cover a frame for a greenhouse or shade cloth instead? Im going to be using an evap cooler, misting system, fans and vents.

Comment by Bob Campbell on March 3, 2012 at 11:42pm

1) What if my pump dies?

2) What if I get a leak?

3) What if the plumbing clogs / blocks?

What if, what if, what if...

Then you figure the level of risk you are willing to take, and take it knowledgeably.

You are right to look at possible disaster controls, but I know someone who is raising Mozambique Tilapia in a child's wading pool, in 45F water with no air stones or filtration.   I personally feel it's cruel, but it proves that Tilapia are adaptive and strong. If a disaster happens go to Walmart and buy a wading pool. 

By the way I recently saw a cattle feed tank being used as a fish tank.  The guy painted the inside with a one part pool paint (not epoxy), and has had no problems from the galvanized steel.  He had a pond filter and spillway running the water.  Total cost about $500.

Comment by Bob Campbell on March 3, 2012 at 11:26pm

David that Chop 2 sounds good, especially after my experience today with submersibles.  I have an external 3600 GPH pump that might be too big, but I'm temped to try it.  Maybe I could raise stream fish

What are you using for a pump?

Comment by Bob Campbell on March 3, 2012 at 11:12pm

Thanks John, 

I read Affnan's description a few months ago, but the link you sent is much more detailed.  I remembered that he liked a 2" opening at the top of the stand pipe so I did that.  I had a piece of 4" in the shop so I used that for the bell, but he suggests 3". 

My tail piece is 2" rather than 1" so I'll try reducing that down to 1" tomorrow.  Then the only difference will be the 4" vs 3" bell.  But it's currently working very well with only an 8 second delay from the time it starts to draw air.   Then a really big burp and the siphon is broken.

Thanks for this link.  It's much better than the one the one I had before.

Comment by John Malone on March 3, 2012 at 9:28pm

Hey Bob,
Have you read the blog of Affnan?
http://affnan-aquaponics.blogspot.com/2010/02/affnans-valve-detaile...
His siphon designs are so good that they name the design after him. It's a very worth read and very detailed.

Comment by Bob Campbell on March 3, 2012 at 7:56pm

Wow, John are you good at wrapping presents too?  The liner looks great!

Comment by Bob Campbell on March 3, 2012 at 7:52pm

I two weeks ago I spent about 30 hours fine tuning my bell siphon, and watched it work flawlessly over the next week.  Today I walk in ready to paint the room, and discover the siphon is not breaking.  So I started to make small changes to see what might help. 

To speed the process; I incorporated another old submersible.  It soon it tripped the GF,I and then I discovered oil in the water.  The seal had leaked!  So I spent the day fixing the siphon, and cleaning up the oil spill from the oil filled pump.  I hope oil filled submersible pumps use fish friendly oil.

I finally got the siphon to work even better than before, but I sure would like it if a hydromechanics engineer could come up with specific requirements for a working bell siphon.  It's frustrating to spend so many hours guessing at what will make it work!

This is just my uneducated take on bell siphons, but here are some rules I think might be important. 

1. The intake area at the bottom of the bell should be more than adequate to handle the maximum siphon flow.

2. The distance from the top of the bell should provide an open area equal to the top of the stand pipe. 

3. The tail pipe (drain pipe) should not be immersed in the sump tank.

4. The volume between the bell and the stand pipe should be equal to the volume of the stand pipe and the tail pipe.

5. The top of the stand pipe should be larger than the stand pipe

I'm pretty sure the first three are important, but I'm just guessing at numbers 4 and 5.

There has got to be a math formula that would provide the important dimensions.  Anyone know an engineer or physics student looking for something to prove?

Comment by John Malone on March 3, 2012 at 2:32pm

OK, NOW I'm making some serious progress.   My college friend showed up all enthusiastic, so I asked him to fill in around the fish tank.  DONE!

Ordered two tone of lava rock, which arrived.  I need that around the back of the house.  DONE!

Hmmm,  time to put the liner in the fish tank.  DONE!

Thanks heaps to Ethan.  Oh, this old man bent his back a bit too!

Comment by Bob Campbell on March 3, 2012 at 12:16pm

Sorry, that link to my video about the no hole aquarium overflow is...

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