Backyard Aquaponics
A place to discuss aquaponics

Yeah, 150mm x 6m filled with scoria.

Ok, going with a CHIFT PIST system (all that drawing wasted!) and am wondering about the best way to drain into the grow beds. In the below picture you see my tank overflowing into the grow beds which drain into the sump which pumps into the tank. There will be more grow beds, this is just to illustrate the question.

If I put the opening for the 40m overflow at the bottom of the tank, say 10mm off the base will this act sufficiently to draw up solids? I figure if my drain is just a pipe coming out the side of the tank, the surface will be drawn off (along with any precious fish food) leaving the solids to get thicker on the bottom. Is this how everyone does it?

Also, I thought about putting the inlet pipe at the bottom of the tank pointed sideways which would circulate the water and push solids towards the center outlet pipe...but this would remove a major source of aeration (water splashing in). Thoughts on that?

I have to say that I liked your 2nd system on the bottom of page 1.
It is similar to the system that I have just put together. As they all say it's good to start small and expand.

http://backyardaquaponics.com/forum/viewtopic.php?f=45&t=3929

It's a simple system for a newbie. A pump from the tank up to the growbeds as flood and drain. 15 minutes on and 45 minutes off with a slow drain directly back into the tank. Good aeration and simple.

Could be easily expanded with more growbeds and a little more plumbing underneath the grow beds.

Will be buying some silver perch as it starts to warm up and will add 2-3 more beds then.
Solids are dealt with by using a tap on the side of the tank. hose on the inside attached to a rod. 5 minutes once a week to suck the solids off the bottom and into a bucket. pour the water back into the grow beds.
Make sure you put the tap in before you fill it with water. Learn by my mistake.

If you sink the tank into the ground a little the grow beds would be at a better height..

Good luck with what ever you come up with.

http://backyardaquaponics.com/forum/viewtopic.php?f=45&t=3929
Sorry, I'm still learning.

Thanks Gilly, excellent tip about the tap and hose. Is this what everyone else does as well?
If the water was stirred up every time the pump ran wouldn't that eventually get them out? I like the idea of the tap for really stubborn solids but thought my drain layout would reduce maintainence needs like that. Would that not be the case? Does yours get stirred up but still need a weekly clean?

I would go with that just drill 2 rows of 10 mm holes around the bottom of the pipe and put the pipe on the bottom

I have a Aqua One pump 1200 ltr/hr that goes on the side of the tank rather than one on the bottom, so doesn't do a good a job getting the solids off the bottom. The system is small at the moment and mostly runs itself so any interaction (cleaning the bottom) gives me satisfaction. What can I say, I'm easily pleased.

I will be reading this thread with interest to see what you come up with.

A major source of aeration is done on the drain cycle as the water is drawn out of the GBs and also as it returns to the sump tank...air can be added by putting in a venturi on the pump pipe as it enters the fish tank

Here is a shot of what I mean...
20mm pipe entering fish tank,
pipe angled so that water swirls around the tank (note bubbles just after the pipe exit)
little black nozzle screwed into 20mm pipe (irrigation fitting) sucks in air as the water passes through the pipe

You can do the CHIFT PIST and still have the pump inlet splash a bit while swirling the water around and still get solids removal. Especially once there are fish to swim around in the tank and help swirl the solids.

Only suggestion on the venturi drain set up I have, Use a Tee instead of an elbow. A bit of shade cloth or screen over the pipe openings can help keep fish from going exploring in your gravel.

For some reason, fish+pumps+gravel dont mix

Hang on, if I put shade cloth over the outlet...the solids won't be sucked up. It looks like Gilly's tap system is essential to get solids out if I don't want to suck out too many fish.

It's a fine balance between getting all the solids out and keeping your fish in/safe. A two inch fish can go through 3/4 inch pipe and 6 elbows so I've learned that some netting over the pipes is a good idea. Solids still move through the system, you may just need to clean the netting over the pipes every so often.

I have agai

n learned a lot from this discussion, thanks

but I have some suggestions:

on the first design: reversing the flow in the NFT gutters will save you a lot of energy
you only need to pump the water straight up to gutter height, the rest is gravity = free
much less piping

don't cut a V out of the gutters, this will weaken their rigidity and call for more supports.
drill holes in them instead: easier, faster, putting a lid on the unused ones will limit algae growth and clogging.

on subsequent designs: I am in favor of a fish tank siphon overflow system
no pump in the fish tank, always water in the fish tank even when something goes wrong

have you considered lifting the fish tank off the ground?

have the fish tank overflow into a small but high settling tank which overflows into the highest NFT gutter ( only a few centimeters of level difference needed each step) the trick is only to slow down water speed
this system will be eliminating the solids continuously out of the fish tank, which is where they are harmful, as they are O2 gobblers.
much better than periodically.

have each gutter equipped with a small drain and a big overflow, both to the next gutter
no need to feed each gutter separately, each gutter feeds the next, less piping.

After the series of NFT gutters, one (or more) growbed(s, in series or parallel), as already suggested. More planting surface.

Not a siphon or other device (which calls for a sump), but the pump located in or next to the growbed actioned by one (or two: low and high) level switch(es) (as used in washing machines - cheap and very reliable, scroungeable): each time a certain level is reached in the growbed, water is pumped to the fish tank, which then overflows into the settling tank, which then overflows into the highest NFT gutter, which overflows and drains into the next.
The growbed acts as a sump.

This way you create ebb and flow in both gutters and growbed(s) (though flow will last longer in the upper gutters).
Aeration issues solved by ebb and flow: no need for air stones.

size of the growbeds and the pump will determine ebb and flow frequency.

periodically drain the settling tank onto the growbeds or, even better, to a worm bin
periodically feed the worms to the fish

comments please

frank

Sounds awefully complicated to me Frank... and requires both the fish tank and settling tank to be above the height of the top pipe (albeit a few centimeters each step)...

Given the spec (ala TCL's drawing).... this would require the fish tank to be that high that you couldn't reach it... or would severely compromise the number of pipes that could be utilised...

IMO... a flat table... ala traditional hydro.... allows for much more ease of operation and flexibility of design...

Or a series of cascading pipes suppied by a seperate pump .. from a sump...

NFT also requires two major factors... sufficient flow rate and/or supplementary oxygenation... and the removal of particulate solids...

Without all of the above NFT will either return miserable results or fail completely... due to lack of oxygen to the root zone... solids clinging to the root ball, leading to channeling and either root rot due to sections of the root ball developing anaerobic zones, or sections of the root ball drying out.

The adoption of multiple level switchs, cascading pipes and a header tank.... just un-necessarily complicates things IMO...

And I'm unsure from your description just how the water returns to the fish tank... without a sump

Chift Pist.... one pump in the sump... to fish tank, that overflows (maintaining a constant height)... to supply the growbeds (solids extraction)...

Is the easiest, cheapest, most reliable and efficient design IMO... a small pump, running from the sump to supply the NFT, with airstone(s) either in the sump or in each NFT channel is the way to incorporate them IMO....

Acheives all design criteria... and is relatively bulletproof.... failure of pump in sump to growbed.... no real problems (as long as fish tank has airstone), as the growbeds will survive for long periods... and the NFT will continue to function as per normal, returning to the sump...

Failure of the pump to the NFT channels, would result in death of plants in the NFT, if not addressed within a reasonable time.... but wouldn't compromise the rest of the system..

I think you have not understood: it is quite simple

will make a drawing

it is said this says more than a 1000 words

frank