First time poster, Long time lingerer :p
These problems have been occurring for a long time and I have never found a solution so the plants have suffered for some years. :(
Right now there are some plants growing in a homemade tube system almost exactly like pictured below. The ingredients consist of PVC fence posts, PVC pipes for the manifold, plastic reservoir, PVC glue to hold the manifold together, Plumbing grade rubber tubing to connect the Rubbermaid top-off reservoir, a pump, and Aquarium Goop. The reservoir holds about 15 gallons and with the tubes included there is about 20 gallons in all. The top-off res hold 50 gallons.
Now here is the problem and hopefully some knowledgeable person can help because I have exhausted my brain in trying to figure out what the problem is and Google offered me no answers!
Many different strains(Indica & Sativa) and different types of Nutrients(BC Hydro, Dutch Master, and General Hydroponics) have been tried all with the same result/problem. The plants grow fine in the clone/vegetative state. In fact, they grow great! The problem occurs only in the flowering stage. Two weeks after inducing flowering the PH will start to drop. When the nutrients are first added to the reservoir after a nutrient change the PH is at a healthy 5.6-5.8. Within 24 hours the PH drops to an aggravatingly low 4.4 while the PPM stays the same! This means that 40ml of PH-Up has to be added regularly on a 24 hour basis to get it up to around PH 6.0!
Now, I have read that PH levels may drop because the plants will eat more water and therefore leave more nutrient solution in the system causing PPM to rise. I would agree that this is the problem if only the PPM did rise but it doesn't.
Needless to say, all this PH fluctuation wreaks havoc on the nutrient availability of the plants. There has never been a healthy crop and it is sad really because from what I can tell everything has been done by the book.
The water used in the system has a natural PH of 7.0-7.1 and a PPM of less than 100. The plants sit in small four inch pots with aquarium grade stones.
The nutrients used are General Hydroponics Flora Series at a ratio of 1-2-3 during bloom as indicated on the label. PPM has been tried anywhere from 700-1300 during this stage with the same result. A ratio of 1-1-1 has been tried and the Lucas Formula has been tried as well.
What am I missing? Why is this happening? Is there anyway to fix this problem? Any help would be greatly appreciated and if more info is required from the reader please let me know and I can provide it :)
