Backyard Aquaponics
A place to discuss aquaponics

Hi - I'm working on plumbing my new setup which will be a ~500 gallon timber fish pond set in the back patio, going to a grow bed about 15' away (on the sunny side of the house). It's going to be sumpless for now so either CF or I deal with the water level changing.

I'd rather not penetrate the pond liner, but I need to bury the lines (3/4" black PE). Very quick question: is it okay to have the line pass over the top as long as I keep it full of water so the siphon stays? It's okay if it stops working every 2 months but not if it stops working every two hours (since the pond is the low point, the failure mode is a full pond).

Or am I being chicken about penetrating the pond liner? This is going to be very hard to access when it's complete so I need a good reliable setup. I've attached a terrible drawing of my intended setup.

Thanks in advance for any help! I searched but I couldn't quite make sense of some of what I was reading.

I'd rethink that pipe size. What size return pipe are you going to use?

Thanks for the reply - this is absolutely the right time for me to be making these calls! Polymeric sand goes down on Sunday.

I was thinking about running 3/4" all around. I am doing a continuous flow experiment with my current (100 gallon) setup to see how the plants like it and it seems like a CF system won't need nearly the throughput of a F/D system. My 100 gallon system does well on 1/2" with flood/drain, for what it's worth. Obviously if I go CF then the return pipe will be the same size as the outgoing.

To be honest, the primary purpose of the grow bed in the new system will be filtering and keeping the fish healthy, so that's coloring my planning somewhat. The tank will not be heavily stocked.

Are you thinking bigger? Feedback greatly appreciated until Sunday

The return piping needs to be much bigger. The return flow will be by gravity fed, not pump fed, correct? How much of a difference in height is there between the fish tank and the grow beds?

The siphon in this application is often referred to as a "no holes overflow". Personally I would not recommend them to avoid penetrating the liner. Get you confidence up order some uniseals and penetrate the liner.

NHOF are seriously unpredictable in their reliability.

As to your pipes sizing there are many threads talking about this. I've done a couple of detailed posts about how to calculate the friction losses through your pipes and hence how to design your feed pipes and drains but if you don't want to go to that level of detail a simpler design guide is...


Keep the velocity of the water in your pipes to less than 1m/s.

V=AQ

V = velocity in "m/s"
A= Cross sectional area of the inside of the pipe "m2"
Q= Flow of water "m3/s"

*facepalm* Of course. That makes sense. It's not a lot - 24"? 36"? I guess I will get off my butt and dig up my textbooks and figure out the right answer.

That's good info. I think I will do a uniseal and keep the 100 gallon stock tank as an emergency fish kennel on the off chance I need to empty the big tank for maintenance; and "no holes overflow" gives me something to search on to keep me occupied.

Thanks so much for the answers so far and please feel free to keep them coming!

If you are willing to go to a text book these might help.

http://www.backyardaquaponics.com/forum/viewtopic.php?f=8&t=21045&hilit=simple+math

http://www.backyardaquaponics.com/forum/viewtopic.php?f=14&t=21129&hilit=xtutex

why don't you put the pump in the FT?

if you are using a 500g/hr pump you will need about 1" pipe for the pumped flow and 1.5" for the return depending on the height.

there are plenty of pipe calculators on the web:-

http://www.calctool.org/CALC/eng/civil/hazen-williams_p

Good question about the pump: in the end, I decided I'd rather not try to run power to this installation. Doing it the truly right way was going to be expensive and unsightly.

I'm going to hit all this useful information and then do some mock up tests with my trash can and rain barrel. Thanks everyone!

[quote


*V=Q/A

I tried your equation and was having trouble making sense of the answers. When I started tracking units, it became apparent.

Yeah that is why imperial can be such a pain in the neck. I like feet, inches pints acres and a few other units because they are easy to think in but when it comes to calculating anything give me metric every time. With Imperial unit s all your formula need to include correction factors. Not intuitive and confusing

I meant when you track the units from the V=AQ equation, the answer ends up with units of X m4/s.
The equation must be V=A/Q to get units of m/s

Agree Bunson. All been discussed many moons ago. Please people use the search function, it's there for a reason.