HUGE pH swings, NOT EVEN FEEDING YET!

So this is my first hydro grow, and I am using a 6-pot "rubbermaid" bubbler/drip ring system. The reservoir is about 20 gallons that I filled with RO water 3/4 of the way, and 1/4 of the way with de-chlorinated tap water.
I started the system out just below pH 6.0, and currently have one seedling (in rockwool that was ph'd down for 24h before being put in) sitting in one of the 6 pots. The roots have grown down through the bottom of the pot, into the bubbling reservoir...but the plant is turning yellow (already pulled 1 seedling because it died).
I check the pH 1-2 times a day and within the day, it creeps from <6.0 to >7.0 and I am not using ANY nutes. I soaked the reservoir in bleach water to sterilize it beforehand, but the water appears cloudy, I lightproofed the reservoir as well...please help I am lost.

Dump the water. Before that get some buckets fill it with tap water and let it sit there so the chlorine can evaporate and use that water.

Do I have to let it sit? I have been using an aquarium product that removes chlorine and chlorides from tap water to make it safe for fish and plants..I figured it would be OK..

infinitescrog said:

Do I have to let it sit? I have been using an aquarium product that removes chlorine and chlorides from tap water to make it safe for fish and plants..I figured it would be OK..

Click to expand...

Doesn't that stuff just convert it to an amonia? Do you have a biofilter?

I do not have any type of filter on the system...I don't know how Chlorine (Cl) can be converted into Ammonia (NH3) by any means, but I also have no idea how it rids the water of chlorine...however; the NH3 would explain the cloudiness and the pH + spikes....I guess I didn't think of this do you think thats the problem?

Hey man,

Don't sweat the spikes too much...most people go through it with reserviors. Think of it as the nature-of-the-Beast.

Eventually when you do res changes--you'll anticipate it. So just use your Ph down. Try to note how much it goes up. So if you are going from 6.0-7.0--then when you change the res...just make it 5.0...so it rises to 6.

If you are checking your res every 24 hours...make adjustments as you go along. It will smooth out eventually.

If it goes up rapidly in the smooth times on a regular basis...it could be a problem like root-rot. But when you are using fresh res's...it's acceptable.

We all go through it (on the most part)

Alright...I'm going through like 5-10 mL of ph - a day i'd say, and the seedlings get yellow and slowly dry out and die...now the seedlings I have in rockwool (not in the bubbler system yet) are turning yellow, is it possible to have a N deficiency this early? Plants are about 2 weeks from germ and still only have 2-3 sets of true leaves, no branching....

I think either the Rockwool is too wet or your plants are hungry.

You don't set PH for straight water setting the PH helps with the break down of nutrients only, so if you have no nutrients to worry about breaking down then PH is pointless. Yeah it is true MJ does like a slightly acidic environment and if you want to split hairs on this PH 7 is neutral just keep it under that. I personally grow seeds and clones at 8.0 PH straight water, I don't care one bit about PH until I add nutrients.

You'll see pH swings without adding anything because of CO2 content. Without going into a lot of boring chemistry about equilibrium reactions, I'll just explain that CO2 forms carbonic acid in water (just like in a carbonated beverage.) This will cause big swings in unbuffered solutions. A buffered solution is one that contains a weak acid or weak base, and that will help hold the pH within a range (again, due to boring chemistry stuff.) pH Up and pH Down solutions act as natural buffers because they are weak acids and bases, and as you add it to your res to correct the pH, the more stable it will become.

thank you eagle...and boring chemistry is my life, I am a biochemistry major. I understand the science behind what you are saying I didn't realize it would take place so quickly I haven't really read of others having to use as much acid as I am to buffer.