Backyard Aquaponics
A place to discuss aquaponics

maybe 3 meters of 19mm poly pipe (including the 1m rise from the tank surface) can get an exact length tomorrow arvo if you want

How cheap can I go? Is this okay? There would only be the height of the tank, 850mm for it to rise, the rest should be pretty flat to the grow beds? Of course it will not allow for future changes though, but at that price, it should be replaceable.

probably, you'd probably get 1200L/hr at your grow bed height.

Another issue with the smaller "powerhead" pumps is that they are prone to blockages from leaves and debris. IMO I would look for something that can handle some solids. Keep in mind this is the core of an AP system, you can't really afford it to break down.

Tim is right, i didn't want to scare you off!

I found that with my 3M 3500L/hr pump (i think) i had to remove the somnge filter as it blocked very quickly

Steve

Hi NV,

I use small aquarium pumps in my system but my fish tank is in my shed so it is not exposed to leaves and other wind-borne debris. The first thing I do when I open the box is chuck the sponge filter away and I put bypass valves into the outflow so that I can run the pump unrestricted.

I also run a couple of small pumps in my tank so that, in the event that one of them fails, the other will keep the fish alive....cheap insurance. One pump is set up to water my small gravel growbed and the other runs water through my bio-filters. I use a small air pump (with four outlets) to keep plenty of DO in the system.

Just by way of guidance, the larger of my two pumps has a nominal pumping rate of 4500 litres per hour......but it drops by a third (to 3000lph at a head of just 1.2 metres.

Gary

I use the powerheads too. Run one for four years plus 24/7 without a hitch. No cleaning. I did break the ceramic shaft in a clumsy attempt to see if it wanted a clean once. Then ran it with the shaft snapped for 2 months before i got another hehe. This is a 20 watt servicing the DWC system.

A 35 watt services the greenhouse pond, 2400 lph. At 1.4 metres head will turn over 1200 lph. Twice the pond volume per hour, happy with that.

My herb garden kokopu tank (nz native trout) runs on 7! watts. Cheap!

I too discard the sponge filter, and I too have no leaf debris to contend with.

I've heard far more expensive pump breakage stories than powerhead breakage stories.

I've had a Pondmaster Mag 2 going quite some time. First it was watercooling my computer, once aquaponics came along the computer got shafted of its coolness. That's OK, the fish like it better. (Picture Tilapia wearing sunglasses )
At least 3 years in the computer and now almost two years in AP. Running 24/7. I am starting to think about putting a new pump in just in case it goes on me, but if run as always on, they will last a long time.

I think this would be an appropriate thread for this question.

I've been trying to get an idea around what sizes of valves and pipes I need for various bits of my system. The very helpful people at my plumbing supply place gave me a table that showed various rates of flow by diameter of pipe and pressure. Only problem is the table only went down to 20psi which is the equivilent of 14m of head pressure. Since many of the rates of flow will be with 1m of head pressure or less turns out that they wern't very helpful after all (especially since I told them how low the pressure in the system was going to be).

Can anyone point me to a table or formular for calculating this sort of thing?

Thanks for that NJH but I must be doing something wrong.

see pic

Pd = pressure drop in pounds per square inch / foot

Q = gallons per minute

C = factor (friction loss coefficient) - the higher the C factor, the smoother the pipe. Typical C factors used in design, which take into account some increase in roughness as pipe ages are as follows:

Polyvinyl chloride (PVC) - 150
d = actual inside pipe diameter in inches

I thought the the pressure drop could equate to the pressure in meters of head but....

20 psi
2" diameter PVC pipe

20= (4.52 x G/min)/150 x 2

6000 = 4.52 x G/min

G/min = 1327G/min

The table I was given had a rate of flow through a 2" pipe of 161g/min @ 20psi.

Confused again

My pump had a chart with it that showed how much water would be moved at various heads. As a general rule, use larger diameter pipes to create less resistance to the water moving. Every corner you turn or valve that you go through reduces flow.

Here's the (simplistic) chart for my pump:
http://www.drsfostersmith.com/product/a ... #title%202