Backyard Aquaponics
A place to discuss aquaponics

Bingo - what a great find. I must have goggled a hundred times and got poo. I clicked on the link and checked it out - it is for sure less than 20 kilometers from my house. I am going to Korat in the a.m. for a meeting so right after lunch I will be in his shop. When I goggle things I seem to get all sorts of USA advertisement type links which I need like a hole in the head. I'll let you know what I find out tomorrow because my wife loves to brouse in fish shops.

Duinui

I have considered your idea about changing one or two of my grow beds to gravel, problem is the GB is 24 to 28 inches deep. Does that matter except that I am using a lot of gravel. I know the GB only needs to be 12 inches deep. The only reason I am using coir and hulls is that I did not know you could grown veggies in gravel, otherwise I would have built the GB different and used gravel. I also did not know before that the gray gravel works so well or that it was workable at all.

I think you will start to have filtration problems as the fish get bigger, so if you can change any of the gb's to gravel, it will help.
With a system that has twice as much gravel volume as FT volume the recommended stocking density is about 20kg/1000 litres or cubic meter.
If you start to harvest your fish at 600 grams (and assuming you have around 300 fish left) your density will be about 12-13kg/m3 with very little filtration.

I don't think a GB of 28 inches will be a problem, you will probably want to arrange it so that some of the water is drawn from the bottom of the GB.

It really depends what you want to achieve, the other option is to reduce your stocking density so that the filtration you have can cope with it.
I'm not aware of a system that has coir as the sole filtration mediuim, so I can't comment on its effectiveness in that area, I have read that it absorbs too much water and will be too wet in that situation.

I agree that the coir would stay too wet in a continuous system. Each GB is approximately 120 cm X 120 CB by 65 + cm deep. I have a drain on the front near the bottom - a 3/4 inch pvc pipe. See photo near beginning of this thread. I can put a drain in the box anywhere I want. It is only cement block. What do you suggest? How would you build it? What kind of a SLO would I use in a GB? Placed where? How big? If I put a SLO in the GB - it will accomplish what? - I assume help remove solids. Sorry for so many questions but please remember that until a few days ago I had no idea what a SLO was or that there even was such a thing.

I got an Ammonia test kit. Also one for Nitrate, one for PH, and one for Nitrite. I got all four today for a total price of 1265 Baht. API Test Kits.

TEST KITS AND FISH SUPPLIES IN KORAT -

DIRECTIONS - coming from KK on highway 2 coming into Korat you will see Macro on your right, then the Bus Station, and then St. Mary's Hospital. Soon the road will dead end - you will turn left or right. If you turn right you will still be on highway two and go into Korat. If you stay left, just after you pass Big C on your left you will see the fish stores. If you go all the way through the turn you just passed them. Mr Fish is on the corner of highway 2 right after you pass Big C coming from KK On the corner there is two fish/pet stores. The first is Mr Fish, the second is Animal (Animal does not like people to park in their lot and shop elsewhere). We shop at Animal all the time - they are both good stores and well stocked.
The telephone numbers are: 044-272081 or 081-8789194.

Well done on the test kits, it should give you some peace of mind (assuming the water tests good, hehe)

I think you're kinda still missing the point of a GB.
You take the solids, fish waste and uneaten food etc, out of the Fish Tank and put them in the GB.
Once in the GB it breaks down over time, and the bacteria (which eventually covers just about everything in the system) converts the nasty chemicals given off by the decomposing solids into useful food for the plants.

The SLO goes in the FT and lifts the solids into the GB, clean water goes back to the FT/ST.
In your case you have no sump, so you don't need an SLO because your pump is in the Fish Tank.
The pump will pump the solids straight into the Grow Beds.
For constant flood, you will need to add a standpipe and a gravel guard, the water fills up the GB, when it hits the top of the stand pipe it overflows back to your FT.
The Standpipe Gravel Guard is a 100mm piece of pipe with holes drilled all around it for the water to flow through.
On my CF beds I put the holes up and down the length of it, but have more at the bottom.
This, hopefully draws more water from the bottom of the GB than the top, keeps it better aerated.

You seem to have confused yourself over the last week or so.
It's a lot of information to take in, hang in there, you'll get it

Got test kits today. Nitrate 5.0 and Ammonia O ppm (mg/L). I understand Zero and I love it - but what the other stuff mean? I got it off of the card.

9 more dead today.

Question: My plants look sort of yellow. I think that is from water that lacks the proper nutrients. But the last few days many, especially tomatoes have a center of the plant that is beautifully green and healthy looking while the older leaves and stems look sort of yellow. Anyone know what that means?

Ammonia 0 is (of course) exactly what you want to see.
Also Nitrate at 5 is a good sign, it means you have both types of bacteria already established in your system.
Yellow leaves are generally a sign of Iron deficiency, this can be cured by adding Iron Chelate.
You may find this hard to get, I did.
What is your PH?
High PH prevents plants from taking up some nutrients, that is where the Iron Chelate comes in.
You can try here:
http://www.higreenfarm.com/site/node/28
Fe-EDTA is what you're looking for, Iron Chelate or Chelated Iron.

Also bury some banana skins in your GB, this helps with Potassium

John I think the PH will be high, due to concrete.

Today I did a test for ammonia, nitrate, nitrite, and PH. Yesterday I did not do the test correctly for nitrate so today I sat down and read how to do each test correctly. The results: ammo 0, nitrate closer to zero than 5, very hard to tell because the color was exactly between the two colors representing 0 and 5. Nitrite 0.25 and PH 7.6

As of noon today I had 7 dead. Don't know after that - had to go to town on business and just returned after 10 p.m.

I plan to change over one GB during this next week. From my present setup to gravel filled and continous flow. I plan to put a 3/4 inch standpipe in the tank that will come to within 5 inches to the top edge of the tank. I will attach it to the 3/4 inch pipe I now have in the bottom front of the tank for drainage. I will make a gravel guard out of pipe approximately 3 or 4 inch diameter with holes drilled in it to allow water in and gravel out. How far into the gravel should the gravel guard extend? To the bottom of the tank? What? I will fill with gravel to within 3 inches of the top edge of the tank. That should leave the water level right at two inches below the level of the gravel. I can adjust the water level to gravel level simply by adding or removing gravel. The water will come in over the front of the tank directly from the FT since I have no sump tank. Does this sound like a doable plan?

Sounds ok to me John.
The gravel guard should go to the bottom, you never know when you might need to get a hand in there.
Clearing roots, fixing a plumbing joint, whatever.
Don't glue anything, you may need to change standpipe length, perhaps even pipe diameter, convert to Siphon, whatever.

Your water tests all look good, which is as perplexing as all my attempts, nothing to explain all these deaths, I have stopped even testing my water now, it's actually more stressful knowing that the testable parameters are fine, and still they die.

Good luck with the modifications, and as always, any questions, please fire away

Dui.

What is the smallest size of gravel that may be used in an AP GB's? How small of diameter can the holes be in a gravel guard to effectively let water flow in?

What is a Yabbie? Are they good to eat?