Aquaponics, take 3
Posted on Jun 21, 2008 under Aquaponics, Gardening | 4 CommentsWith some help of the nice people over at Backyard Aquaponics, I now know why my tomato plant didn’t grow. The gravel I was using as grow bed medium was the wrong type of stone, probably limestone or marble. This caused the pH of the water to rise up to 9.0 and inhibit the plants nutrient uptake.
They say that lessons learned the hard way stick better, I agree. Before getting the next trunk load of gravel and take half a day of washing it and shoveling it into my grow beds, I will take a sample home to test. I’m quite sure I will not forget to do that!
Well, back to aquaponics, square one. I got a bag of Seramis expanded clay granulate to use as grow bed medium. This stuff is specially made for plants, so it should do the trick. It is a lot more expensive than gravel, but it has a few advantages: the very porous material is very lightweight and the capillary action will suck the water up for quite a few inches. Because of this it can be used in a constant flow system with a constant low water level, so no more messing around with loop siphons. I used a small square container as grow bed. A hole in one corner is covered with a drain sieve which prevents the clay granulate from washing into the fish tank.
I’ve planted some lettuce into the grow bed and threw some basil seeds in. Stay tuned for their progress!
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June 22nd, 2008 at 6:57 am
Where did you get the expanded clay? It looks just like small LECA or hydroton from the hydroponics store.
Hopefully it will work out for you.
June 22nd, 2008 at 8:11 am
Seramis can be bought at most garden and plant shops here in Germany. It is a lot like LECA, but it looks way better.
January 30th, 2009 at 5:48 pm
can i used the coral stone found in the sea shore this stone is light and absord water too ex clay is hard to find in our country i live in cebu ,philippines i hav gone from store to store looking for the exclay for my grow wat other medium can you recomend tanxs
January 31st, 2009 at 4:12 am
Felicito, I have seen crushed coral used as a grow medium in aquaponics before, so yes, it should work. Just make sure to give it a good wash before using.