Growdude said:
If its a big grow cleaning hydroton is not practical.
I'm not commercial and just said forget it and buy new each grow.
I thought most commercial used Rockwool.
i tried several cleaning methods, taking out the rocks and soaking in bleach removing roots manually, that was way too hard, next I tried putting in the oven, also a big fuss. nowadays, I just remove the rootball at harvest soak with h2o2 35% overnight, flush and grow on. never seen ill effects of some roothairs here and there. of course i also add h2o2 in very small amounts to the res during the grow. I'm thinking, maybe I can do just that on a commercial grow. it is the same or less labor intensive than bringing new rocks and removing the old ones. it would require a worker for a whole day removing root balls as thorough as possible... a day or two worth of labor cost is not that much when compared to the value of rebuying new medium on a big scale. if i am to estimate the labor time, my estimate would be that a good worker would clean 1000L of growrocks every hour. for 7 hours labor it is 7000L if the greenhouse is like a full acre, of tomatoes, the amount of rocks is like 40,000Liters of growrock, which is 6 day worth of workers' wages. I can get from the manufacturer in bulk, 40,000 liters will cost me $6,000-$7000 (don't start at me with online price comparisons :ignore: ) this will produce 8000 tomato plants in 5 liter pots... not that i am decided on type of crop, just taking tomato for reference. the numbers seem interesting at first, but when you add up the marketing, distribution costs and risk factor, it adds up to a fair profit margin...
as for rockwool, it just seems more costly at least in my case. also I think that rockwool is more complicated to manage during the growth due to dripper setups, algae prevention, overwatering possibility etc. it is of course the only medium to use for a DWC or NFT lettuce farm, but I am thinking of more than just lettuce. crops like tomatoes or cucumbers, are much like marijuana, in the sense that they will not grow to full potential with submerged roots, so to achieve good results in DWC, it will require a lid to hold the plant above water level and airstone, something very hard to manage on a commercial level. imagine having to check 8000 buckets every day...
I'm mostly "thinking out loud" now, so feel free to think loud with me. my sample greenhouse is long set up and right now I have a high chance of beginning with a commercial project