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I have been looking for a Hydroton replacement for a while now. As my my small system is inside on a wooden floor, gravel or river rock is too heavy. My local greenhouse supplier gave me a call last week about a product called Gold Label Hydrocorn. A single hydroponic substrate. This is supposed to be a Hydroton replacement so I thought what the heck, and bought a 45L bag. Its about the same price as Hydroton. The media is expanded clay, although not as uniform in size or shape as Hydroton. It is, for the lack of a better word, quite "lumpy" in appearance, which to my mind is a plus because of the greater surface area exposed to the fish water. I used it to top off a 40gal grow bed,and in 3" net pots in the 2*4 DWR. Herbs and spinach in it. Everything sprouted, the fish are still happy, and the water quality has not changed one iota.

I don't know if the product is available everywhere, but here is the website:

http://www.goldlabel.nl

For metal analysis:  http://www.aafp.org/metals.htm

Maybe this will be of use to someone in the community

Ian

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I've heard good things about a product called "Plant!t". It's essentially the exact same thing as hydroton. I haven't used it myself though.

HydroCorn is indeed a suitable replacement for hydroton.  It is the same pH inert, expanded clay material.  It does appear to be a bit lighter than hydroton.

I use both Hydroton and Hydrocorn.  One really big benefit, surface area.  Hydrocorn has far more surface area than hydrocorn.  Downside is it really needs to be cleaned far more than hydroton.  I use Gold Medal brand from Netherlands and Hydrocorn is actually about $10 - $20 cheaper for a 45l bag.

I picked up some bags of sunleaves rocks to fill one of my 40ft grow beds. I really like them compared to hydroton. They don't roll, they don't float and the best part of all is its only $28 dollars for a 65lb bag. They are lite too, they actually feel about as lite as hydroton does. The rocks come in all different shapes and sizes. They look like they could hold some good beneficial bacteria also. A rock the size of a golf ball is really lite feeling. I will try to get some pics up soon.

This material is an expanded clay that I picked up at my local concrete batch plant. It is used for applications where regular concrete is too heavy. it weighs about half as much as the typical agregate used for concrete. It cost me $30 for a yard and has worked great in my system. It is very porous and has tons of surface area. The downside is it was very dirty and had many small particles, so I had to wash it several times over a 1/4" sieve and I lost about 1/3 of the material threw the sieve. Even after all that I had to flush my system after it had circulated through the material a few times, because of the muddy water. All of that effort was worth it because I don't have the funds to drop on designer hydroponic media.
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Nice call Roger. Thanks for the post. At $30 per yard that is fantastic. It looks like lava with all the sharp corners melted round. BTW, save the fines for a wicking bed.

Roger Baldwin said:

This material is an expanded clay that I picked up at my local concrete batch plant. It is used for applications where regular concrete is too heavy. it weighs about half as much as the typical agregate used for concrete. It cost me $30 for a yard and has worked great in my system. It is very porous and has tons of surface area. The downside is it was very dirty and had many small particles, so I had to wash it several times over a 1/4" sieve and I lost about 1/3 of the material threw the sieve. Even after all that I had to flush my system after it had circulated through the material a few times, because of the muddy water. All of that effort was worth it because I don't have the funds to drop on designer hydroponic media.

Oh I didn't mean to say expanded clay..  oops, I was told it was an expanded shale product, but now that you mention it, it does kinda look like weathered lava.  The person I got it from was not too familiar with the material, it is something they don't keep around regularly, and special order for specific jobs.  They just happened to have a couple or five tons leftover. Regardless of that, they would not cut me a deal on the price...  But at $30 a yard I couldn't complain.  I liked it because of the weight, size, price and similar appearance to what I have seen on this sight.  I conducted a fizzle test and a distilled water test on a sample before I got it and all seem good, so I bought it.  Other than the amount of effort to clean it, it has been problem free.  I have discarded the fines, but if... when I expand and get more I will definitely save them.

Expanded clay, lava, basalt, shale, etc. is pretty much the same thing as long as its pH inert. They melt it all into lava to make it anyway. I'll call my local batch plant.

Yeah, I wasn't gonna say anything, but watch the pH of construction/concrete/drainage grade LECA. The stuff I saw here from the former producers of hydroton says pH 6.5 to 9. That's quite a range. The type and quality of clay used will determine pH and heavy metal content...That type of quality control (or lack of) is why the new owners of the company that makes hydroton supposedly had a falling out over, and hence it's not being made anymore...(The other side of the story is that a couple of the partners were wanting to edge into the more lucrative horticultural division of the business using clay from the new mine in Slovakia, or Czech Republic...I still get the two mixed up sometimes...) At any rate taking a number of 'acid fizz test samples' would be a most prudent idea...

Why would it be such a bad thing to have media that was a little basic, say 7.5 or so? It seems that everyone is fighting to keep there pH up after a system has aged a little, so why not make a buffer intrinsic to the system? I realize that it is walking a tight rope so to say, so one needs to be carefull, but it could save some head ache in the long run. Anyway, according to some of your posts Vlad (and I agree)the plants don't seem to mind a little higher pH.

Nope ,they don't mind enough for it to matter (as long as you have plenty of the divalent cations that tend to start to get locked out at higher pH levels present in solution). Having a bit of media that doubles as a slight buffer is indeed a keen thing. But media with a pH of 8 or 9 would be a horror. Honestly, I plan on running the new system, long term, at a pH of about 6.2. One the bacterial colony is very firmly established. 

I think Rob Nash uses about 30% carbonate containing media on purpose, for the reasons you described (and I'm sure there are others). I'm sure it might make things less hands on as far as fiddling with buffering goes. But, I don't see buffering as a 'headache'  

I want to run my system at a lower pH than what is generally sold as the "ideal" pH for an AP system though.

Talk about walking a tight rope... Why run a system so low? Doesn't that endanger the bacteria and the fish?

Divalent cations... So you would need to supply calcium and magnesium in forms that didn't increase the pH further? Any suggestions?

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