ppm control
 

To Ron K. hygro@gte.net
The nutrients that I am using are a commercial mix that I bought recently. I checked the ppm on nitrogen and found it to be low, so I am assuming that was the "lighter green" problem. The mix is based on calcium nitrate, potassium nitrate, and micronutrients. It is high in potassium, med - high in nitrogen and medium in phosphorus. I have since adjusted accordingly.
The system I use has the rockwool blocks on a tray that is slightly wider than the blocks themselves.
About ½ of the block is actually touching the water when the pump is on. The other half is suspended over the bottom of the container. With no better way to explain it, the rockwool is corrugated. only some of it touches the nutrient solution.
The roots are a nice white, so I think aeration is not too much of a problem. The pump cycles for 15 minutes on 15 minute cycles.
This is my first attempt at an actual hydroponics garden. I have made previous attempts with complete failure. I have been growing vegetables in the ground and soil for years and I have to say that my plants are the fastest growing and the healthiest <sp?> plants I have ever seen. I just may stick with this hydro thing ;-)
One more question. Because I am a little low on nitrogen, could I adjust my pH up with ammonium hydroxide <household ammonia> I do not want to use potassium hydroxide as I am afraid that it will raise the ppm of potassium in the solution too high. Can I expect precipitation of some of the constituents if I use ammonia? I would really like to give it a try but I don't want to screw up the first successful hydro garden I have had. Thanks
JB

To JB,
Sounds like you have the nutrient solution pretty well under control. Actually, a bit of Ammonia (use VERY sparingly) will help green-up your plants fast. Since you use mainly the nitrate Nitrogen (as should be) a little ammonium won't hurt. Ammonium (ammoniac nitrogen) is absorbed by the plant almost immediately in hydroponic applications because there are no micro organisms to hold it "in check" (slow it down) as in soil. It can do a very quick green job but too much will cause "leggy"
growth.
I would stick to Potassium Hydroxide or calcium oxide for adjusting pH up and Nitric, Phosphoric or citric acid for pH down. in the case of Potassium Hydroxide, since so little is used for pH correction, the addition is so small that only a negligible amount of potassium will be added. All this is basically a repeat of what the folks at the Eco nutrient facility have explained to me.
Ron K hygro@gte.net