I have been growing lettuce for almost a year now in a RDWC system and have come across a weird behavior that prompts this question.
I use tap water (EC ~ 290) with a water conditioner.
I found that in my system the lettuce really likes (General Hydroponics) 5ml Micro, 5ml Bloom, 5ml Grow, 2ml Hydroguard all per gallon.
After pH balance to 6.0 this equals out around 1.5-1.7 EC total.
I have tried to lower the EC slightly to .9-1.1 by dropping the nutrient levels but when I do the pH drops repeatedly very quick. pH will consistently go from 6.0 to 5.7 in under 8 hrs. I bump it back up with GH pH-up and 8 hrs later it’s back down to 5.7 or lower.
If I leave the EC around 1.5-17 the pH stays very consistent for 48hrs or more. Does anyone know why this occurs? I have eliminated all other root rot/bacteria/etc type causes and can repeat this test output very easy so I know it’s EC related. Why?
by Duckmanjbr
2 Comments
It could be how the plants are taking in the nutrients. You could do a test of just the water in a 1 gallon container with no plants and see if the same results occur. If the same thing occurs with no plants then it could be some kind of nutrient block happening
These pre-made nutrients contain a buffer. A buffer is something that resists changes in ph. Do a YouTube search on ph buffers for some great explanations. Also check out a channel called Science in Hydroponics where Daniel Fernandez (or maybe its Hernandez) creates buffers from scratch.
By adding less nutrients you’re also getting less of that buffer. Then, all the things that would naturally cause ph to fluctuate are more able to actually cause those fluctuations.