Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

I'm a big fan of Hydroton, although I know it is crazy expensive...but you will have it forever.  Lightweight and easy on my hands.  Even looks nice.  Ok, I know I'm sounding like a girl here.


What do you use and why?  And if you use gravel, what size and tell us about your source.

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Do you know where your red lava is from?

Homefire said:

I'm using red lava in one tub and a black nonporous igneous rock in the other.

I love the red lava, rootlets grow right through the pores.  I've never seen plants as healthy as these.  Imagine the surface area for bacteria to grow on!

I have noticed that lava as taken from the bag is alkaline.  I had to wash it many times anyway for the sand.




Hydroton shouldn't actually lower the pH, it just doesn't cause the pH to stay too high the way limestone or marble will.  There are types of rocks and gravel that won't affect pH but they are mostly heavy compared to Hydroton.  The Aquaponics bio-filter action is actually what lowers the pH over time and will eventually cause most people to need to add some sort of buffer to keep the pH from dropping too low.

Not trying to hijack this thread, but can anyone direct me to a thread on the pro's and cons of raft growing versus medium growing?


I am using hydroton in my 2 growbeds. I am in the process of increasing the size of my growbeds 10 times.. So I am looking for a better bed for my plants. I want to add rocks with minerals. I am thinking about using hydroton with lava rock and some other rocks. Any suggestions?

How's your pH holding up with the biochar? 

Paul Letby said:

I should have been on here earlier, ha!  I'm experimenting with charcoal as a media as most of you know.  I'm finding that it wicks very well, meaning it's damp on the surface.  Something is precipitating out of the charcoal, near the edges.  Maybe it's minerals? Kinda whitish grey.  I will grow out this crop and then probably remove a few inches and put a bag of hydroton on top.  I need to keep this bed light so no gravel.  This way the surface will stay dry and my water usage will go down.

Rocks have benefits of stabilizing roots, facilitating biofiltration, aeration without continuous air, more forgiving when power shuts down, hosts growth fungi and other beneficial organisms, mechanical filter and storage of nutrient rich solids including fish poop, biochar and bacterial biomass. It's also better for seeding and transplanting. Deep water requires no stones. This could be only choice in large operations. 

Ronald Holley said:

Not trying to hijack this thread, but can anyone direct me to a thread on the pro's and cons of raft growing versus medium growing?



I have had a problem with hydroton getting into my plumbing and the cost.

Now from R&D at the University of Arizona, I am helping to develop a new "hydroton" but locally. Cost, larger stones, lighter, more porous, and Made in the USA are some of the improvements. I have it in one of my new beds, now. When we make up a new supply, I will remove the hydroton from my big grow-bed and start with the new stones.. I am thinking about the name aquaponics stones.

If I can post a picture you will see the new stones in the bed with my tomato plant.

Hey Sylvia, Permatil is my favorite, so far. It's light weight, 1/2" and 3/4" diameter options. It's an expanded slate, dark in color, porous and also easy on the hands. But with all, it increases alkalinity of water, though based on plant performance I trust that pH in beds is lower, particularly at root area where more intensive biofiltration is taking place. Cost is about $6 for .75 CF.

The expanded slate I believe will temporarily increase pH but I have a feeling that property is only temporary.  I'll have to run some more tests to be sure though.

Question:  If you build a tote system, like in Murry Hallam video, how much Hydroton is needed to fill the tote bed to a 12 inches deep level?

About 5 x 50L bags....

Wouldn't that be 5, 50 L bags per bed?


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