Zandor,

Thank you very much for the response. As far as troubleshooting goes, and by way of background info:

I use only distilled water, so theoretically I'm starting out at 0 ppm;

I germinate using the paper towel method (which is highly effective for me - 20 out of 25 seeds sprouted in my latest attempt, 18 of which are now nice seedlings);

I don't use rockwool (I use foam cubes for the seedlings); and

I use granulated citric acid for pH down (I use potassium bi-carbonate whenever I do use pH up).

Also, I don't have a TDS/EC meter, so I don't really know how concentrated my nute solution is at any given moment. I mix the nutes stricly according to the manufacturer's recommendation (in my case, that would be Advanced Nutrients. They provide an online nutrient calculator which can be found at: http://www.advancednutrients.com/nutcalc3public/).

Additionally, I just purchased an external canister-style filter (for aquariums) in the hopes that it will help keep the pH at a more constant level. I've read that these filters promote the growth of beneficial bacteria which denitrify the nute solution by removing nitrite and nitrate wastes. After I install the filter, and as soon as I can determine how effective it is, I will post the results.

Thanks again for your time and attention, Zandor. I sincerely appreciate it.

Green Dreams,
Anchman