Alex's System - New at this game

[alexmac]

Hi, I have never posted to a forum before so this is a learning phase for me.
My son and I have started to set up an AP unit and do need some advice. We are using s/hand concrete stock troughs 2 x 1500lts and 3 x 800lts at least that is what we are told they hold. There are 2 X 1800 across x 500 deep and 3 x 1250 x 400 deep.
The plan (and we have them setup,) is to grow fish in the 2 x 1500lts, yabbies,fingerlings and duckweed in 1 x 800lts on the same level, and grow beds in the two other 800lts. We have the 2 X 800lts grow beds above and resting on the sides of the 2 x 1500lt tanks. The water will be pumped with a submersible pump fitted with a float switch to the grow beds and drain back into the fish tanks. All under cover, glasshouse and shed for fish.
Do you all agree on the lts we are told they hold? The troughs leak, what do you suggest we paint them with to seal them?
How many fish do you consider is a sensible number for each 1500lts?
We can and will at a later date post some photos showing the set up but at the moment we are still living in Heathcote and traveling to Katunga each weekend. When we have settled down at Katunga we will have more time to fill you in with the details and the results of our efforts. regards Alex

[Murray]

Hi Alex,
Welcome.
I have moved your post to a thread of your own. We will all be looking forward to seeing some pix.

[anniefish]

Hi Alex,
If the troughs are full of water and you don't want to empty them, just trickle neat cement above the area that is leaking. If you can empty them, buy silasec and make into a putty with neat cement and while still warm work into the cracks making sure the cracks are dry and clean. Leave 24 hrs then gently fill the troughs. The putty can be used inside or outside of the trough.
Another way is to make a 'paint' of silasec and neat cement and paint the whole inside of the trough. To do this wet the trough, then paint while the concrete is wet, again, leave 24 hrs then gently fill the troughs. Any problems just yell.
Cheers, Ann

[alexmac]

Hi Ann,
Many thanks , the tanks are empty and do not have many cracks to patch up and I would like to do a complete paint finish. I was not sure that silasec was OK with fish have used it on steel sheep water troughs.
Regards Alex

[Jonathan Dyer]

Hi Alex,

Concrete is porous slowly but surely it weeps through the concrete it may not be noticeable but it does happen. Similar in respect that glass is a liquid and in large buildings windows need to be rotated from top to bottom occasionally. More so, even in fresh water the salts over time will slowly seep into the concrete mesh and rust in the middle of the concrete and eventually cracking the concrete altogether. It may take 10 or so years but it requires maintenance although, if worse comes to worse a strong plastic liner fitted to the tank will suffice very well.

[alexmac]

Thanks JD,
Yes I am aware of this problem. These troughs are not badly cracked but I would like to seal them as they are old, leak and would look better painted.
Alex

[alexmac]

Back again I have attached a sketch of our setup as do not have a photo yet.
Have not been up to the farm for a week. The better half is ill and it will be at least another two weeks before we can go up.

We intend to move the water from the FTs via a gravity fed syphon which will be limited to take a max of 500 lts from each Fish tank via the sump. The floatpump moves water from the sump up into the GBs which then drain back via loop syphons in the GBs to the FTs
This allows us to keep the water levels in the fish tanks and sump at a constant level via a ball valve.
No need to top up the tanks by hand at any time.

Hope this all makes sense.
Your comments are most welcome as we are flying by the seat of our pants at the moment.
Alex

[Martin A1]

G'Day Alex!

A great set-up mate but in my view a little complicated.... especially if this is a system you may not be around to monitor for a week or two at a time.

I would have you consider the following ideas:
(1) Join the two large FTs so that the water can level out. Connect (somehow) using PVC with heaps of silicon about half way up the wall height of the FT's
(2) Move your float controlled pump into one of the FTs
(3) Raise the third GB (sump tank) as a duckweed/yabby tank as planned or use as a third grow bed
(4) Have your pump supply water to all three GB's with flow control valve(s) to each
(5) All water drains back via gravity/syphons into either FT which levels out the water across both tanks because they are connected.

Water is a wonderful thing in that it will always find its level. You can use this to your advantage if you think about it in different ways.

Your challenge, I guess, is that you are using concrete tanks which are not easy to plumb with pipe fittings???

Anyway give it some further consideration... you will work it out one way or another. I really strive for the simpler design in terms of water flow management.

Alternatively, you could "try" a continuous flow system and not bother with the syphon drains etc?? Others may have better ideas too....

In any case please post some pics as you progress.

[Murray]

Hi Alex,
Both fish tanks and the collection sump are at the same level ?
If so, then I do not see the need for the sump. Unless you particularly want it as another growing area, in which case it is really another fish or yabbie or duckweed tank. I guess it is just a matter of definition.
Have your pump in one of the fish tanks.
In your drawing it would appear that you are going to level the tanks by having up stands in each tank set to the top level of the water. This arrangement works well, but may be a bit difficult the fit the pipe work as Martin says. Draining from the top prevents fish etc escaping to the other tank.
The pump can run continuously and the grow beds can be drained by siphon loops or a bell siphon. It is a good way to go because it simplifies the operation of the system, no need for timers or float switches..... That way you can purchase a smaller capacity pump. Make sure it is a very good quality pump, because if you are going to run a pump in continuous operation the poor quality ones burn out.
Conventional flood and drain floods the bed quickly and drains slowly, this way, using continuous flow low volume pump and siphons, the bed is filled slowly and drained quickly. The beds are kept healthy and do their job well in such an arrangement.
Re timers, some folk like to fit a timer into such a system to regulate the cycles a bit more, for example, switching half hour on - half hour off. The on cycle needs to long enough to completely fill the beds at least once before switching off. The only down side to that idea is that the bed may be 3/4 full when the pump is switched off by the timer, and the bed will stay that way until the pump comes on again and continues to fill the bed. Remember the siphon won't kick in until the bed is full.
In such cases the 3/4 full bed will not be good for the plants. It may result in the plants drowning a little and growth my suffer.

[alexmac]

Thanks Murray, Martin for your comments.

The tanks are joined via the tee into the sump. The water in each FT is always at the same level and can never go below 1000 lts in each tank. The sump supplies the balance of water required to bring the GBs up to the required level. Each FT has a gate valve so that one may be isolated if required.
The syphons in the FTs are only a device that brings the water and solids from the bottom of the FTs and stops the flow when the top of the syphon is clear of the water. Both syphons must be on the same level.
A ball valve cuts in when the syphon in each FT stop, and runs for only a minute or two before the loop syphon from the GBs brings the level in the FTs back up.
If this supplies too much water to the tanks the loop syphons will cut in before the pump stops, preventing the ball valve from opening. The pump moves more water than the syphons can return therefore the pump cuts out when the water in the sump goes below the float switch.
The water from the FTs can be closed to trickle into the sump thus controlling the time between the pump cutting in and shutting off.
At the moment this is all guesswork until we run the system. However I do have a lot of experence moving water around.

[Murray]

Sounds very interesting, I will be keen to see how it all goes.

I like the idea of using a submerged float switch to provide a level control.
I am fiddling around with a timer at the moment and have employed the same idea to act as a cut off to isolate the timer if the water level gets too low.

[alexmac]

Sorry got distracted and posted twice

[Martin A1]

Hi Alex,

The other thing I fogot to mention is that if the water level your duckweed tank rises and falls significantly each cycle then you may find that the duckweek gets stuck to the walls of your tank.

This happens in one of my ponds and on hot days the duckweed will dry up and die.

[alexmac]

Hi Martin,
Yes I am aware of this. We have a cattle trough 100 mts from the shed full of duckweed and other goodies which drops down when the water is shut off.
The duckweed does not seem to stick to the cement troughs as they remain wet for sometime after the water drops.
When the cattle get to this trough the duckweed lasts only a few minutes.

[alexmac]

Have patched all cracks and will let you know which product in a week or so when I am happy with the result.
We have two GBs filled with washed gravel one planted with mini caulies, celery, cos let, broccolini and one tomato self sown in the earth garden one week old. These beds are round, 1250 across and the gravel is 300 deep.
One fish tank is filled but no fish yet and now in the system it is round, 1800 across and 550 deep.

The pump is in the sump and pumps up into the GBs it takes 3 mins to fill both GBs. (which fill at the moment approx 10mm above the gravel. It takes one or two mins to drain below the gravel surface.
Do any of you see a problem here ?)

The GBs drain via a syphon, both empty into the FTank in 10 mins. The FT drains via a syphon back to the sump which takes 21 mins a total of 31 mins before the pump starts again.
The syphon from the FTank never stops running but has a air hole 50 mm below the current static level which cuts the syphon should the power or pump fail.
We have around fifty yabbies in the sump some big ones but mostly bait size. The PH is 6.2 and the water is dirty, any ideas on clearing the water.
When the GBs are full the water levels drop about 50% in the sump, 25% (cannot go below 75% full) in the FTank.
I could correct the over filling of the GBs by fitting a tap into the pump line or putting more gravel into each bed.
Your comments would be most welcome.
Alex

[alexmac]

at last some pics. Note arrow in pic 4 this is the outlet from the fish tank syphon.

[alexmac]

Re flooding problem.
The pump is a Nova 180 X, .03 hp 25 mm outlet. The main problem with it is that it has a fixed arm float switch and cannot be adjusted.

To try and stop the GBs flooding I am going to put a cap on the end of the fill pipe near the bottom of the GD as I fill about 25 mm above the bottom and drill holes in it until I have it working OK. If this works it will save $s and only take a few mins to do. Fingers crossed!!!!!!!!!!!!!!
Any advice comments welcome.
Alex

[GaryD]

Hi Alex,


The pump is in the sump and pumps up into the GBs it takes 3 mins to fill both GBs. (which fill at the moment approx 10mm above the gravel. It takes one or two mins to drain below the gravel surface.
Do any of you see a problem here ?)

I'd recommend that you only flood your grow beds to about 30mm below the surface. it will avoid root rot and algae problems.

Given that both of your grow beds seem to be supported at a level above the fish tank (and the sump tank), I don't understand why you need a sump tank at all. Why wouldn't you just have one grow bed gravity-feeding back into each of two fish tanks?

GaryD

[GaryD]

Hi Alex (again),


We have around fifty yabbies in the sump some big ones but mostly bait size. The PH is 6.2 and the water is dirty, any ideas on clearing the water.

Your smaller yabbies will live longer if the water remains slightly turbid....it's more difficult for the big ones to see where they are.


I could correct the over filling of the GBs by fitting a tap into the pump line or putting more gravel into each bed.

I'd suggest that you install valves in your feeder lines.....and a bypass line from your pump back into the tank. It will enable you to make fine adjustments to the pumping rate without throttling the pump.

GaryD

[alexmac]

Hi Gary,
I have the syphons in the GBs draining all the water out of the GBs off the bottom. The drain hole in the tank is too high to let all water out and I do not want to put any holes in the bottom. That is the only reason that I do not use flood and drain.
I was going to put caps on and try to control the flow that way.
If you look hard in the photo's and you will see a tee in the top pipe up against the GB that has not been planted yet. This takes water via a 19mm hose from the feed pipe back to the sump. I now intend to enlarge this to 20mm PVC and if needed put a control tap as the water returns to the sump.

While I have your attention Garry a question, Will fifty odd yabbies contribute much ammonia too the system?
The water is from the irrigation channel and rich in almost anything you can name so I am not that fussed to clean it up. I have bore water 7.2PH and good to drink at hand which I will use to clear the fish tank before I put fish in. This will also clear up the sump but the yabbies have plenty of hidy holes.
Alex

[GaryD]

Hi,

Yabbies are like any other fish species......they contribute ammonia proportionate to their size and the amount of feed that they get.

In the wild, yabbies feed on detritus (rotting vegetation) which also releases ammonia into the water.

GaryD

[alexmac]

thanks Garry,
I have been eating yabbies since I was in nappies yet no very little about them. A dam on a property I once owned in the Riverina which we used to drag with a bait net would yeild a large chaff bag full on each drag all big black and blue ones. plus native carp (good cod bait) and the odd redfin.
All these dams are now under control of someone or other and a very nice fine will come your way if you get caught even with a piece of meat on a string.

All the fun has been taken from our lives by red tape.

[oggmttkmbbms]

Thoser black yabbies are best eating as they have not recently shed there shell and the meat is full.yummy:)

[alexmac]

We now have over 100 yabbies in the sump. The system is settling in well. Still some flooding but will fit two 20 mm pvc taps next weekend to complete control of this. Have started replacing gal roof with smoky acrylic sheets.
Will leave gal roof over fish tanks. Should have the South wall filled in next weekend and the East side covered with white hot house woven cloth.
The product used to seal up the tanks is Gripset Multi Purpose Liquid Rubber @ $20 Per lt. Two lts used so far with only part of one tank to go. Gripset Primer was applied first (Bond Crete I think) @ $40 for four lts. NO LEAKS.
The PH is holding between 6.8 and 7.2. Have no other testing gear yet but as both the let and cel are growing we may be heading for Silver Perch into tank shortly.

[Murray]

All the fun has been taken from our lives by red tape.

There is very little red tape around aquaponics as yet, so I hope it stays that way.
Your greenhouse is going along loads faster than mine, the weather has changed and the nights are getting cooler. My water temp is 22 deg just now, so it is holding up well at the moment.
The pH in your tanks is good.