Cripes! I'm On A pH Roller Coaster!!!!

I'm using a General Hydroponics Waterfarm 8-pack for the first time, and I'm having extreme pH fluctuations. The pH rises a full point and a half, almost 2 points in every 24-hour period. Here are the facts of the case -

For various reasons, I took the reservoir and controller out of the system and run the 8 modules as independent units. I have an airstone running 24 hours a day in each module. The plants (BC Seedking White Widow) are about 12-13 inches tall. We're using Humboldt Nutrients Master A, Master B, and Verde, and just switched to a 12/12 flowering schedule today. Irrigation timer runs 4 times a day for a half hour each time, and the roots are growing down into the reservoirs on each module now. Lighting is a 1000W Hortilux Eye Super Blue, temps run from 56 to 59 F at night to 86 or 87 F during the light cycle. Humidity is constant at around 20%.

For a while, we were testing the pH daily in each individual module, and making whatever adjustments were necessary. It quickly became apparent that the pH values in each module variied only slightly each time, so what we do now is take 4 modules at a time, drain the nutrients out of the module into a 5-gallon bucket, test and adjust for pH, and pour it back in over the top of the hydroton. Each day, when we test pH, the reading is between 6.8 and 7.2. Usually around 6.9 to 7.1 I lower it to 5.3 (I know, too low, but it's back up to 5.7 in a matter of hours, and starting on the low side keeps it from getting any higher than 7.2 on the high side). Every day, within 24 hours, the pH has shot up from 5.3 to the high "6"s or even the low "7"s.

This is getting to be a real pain in the ass, and it's not doing the plants any favors. Some of them are showing signs of nute lock, and I'm guessing it's because they're spending so much of their time way outside their preferred pH range. Because of personal scheduling issues I'd really rather not have to do the pH twice a day, but if I have to I suppose i can make it work. It's just going to be a lot more difficult now that we're at 12/12, because we're seldom home more than a couple of hours during the light cycle. As it is, I'm concerned that all the ph Down solution I'm using is driving the TDS higher than it needs to be - readings were in the 600 PPM range when the nutes were freshly mixed, and now a week later they're up in the high 800s.

So I have two questions - first of all, what the hell is going on, and second, what do i do about it? Is there a way to buffer the nutes to keep them within a narrower, more conducive-to-living-organisms pH range? Or should I just put the gear up on EBay and go back to soil grows?

Thanks in advance for any help, folks.

Hey Bro, Where do ya get your water? Tap, well,rain, R/O? What is the PH and TDS you start with.

Have you been calibrating your meter every week and storing it in storage solution? Not doing either can account for wild PH fluctuations. I was in a similar bind, hadnt calibrated my cheap meter in 3 weeks. WOuld knock PH down to 5.6 and the next morning it would be in the mid 6s. Now I calibrate it twice a week and store it in a generous amount of solution, problem solved.

I wouldn't pack it in the waterfarms yet - they grow incredible plants. I have done soil, hempy buckets and waterfarms and the waterfarms blow them away. If you are using new hydroton it will significantly raise the pH every day for awhile but will eventually stabilize - just keep adjusting it. I know that people say hydroton is inert and pH neutral but trust me it isn't - it will raise your pH. I did an experiment a few years ago because I had the same problems with the waterfarms and when I asked for advice people told me it couldn't be the hydroton. I took a 5.5 pH stabilized weak nute solution and put half in a glass by itself and put the other half in a glass with some hydroton pebbles - in 24 hrs the glass with the hydroton had jumped to 6.3 pH.

I don't know why you are creating so much work for yourself by not using the res or controller that came with your waterfarm 8-pack. I suggest you use at least the controller with the GH circulating upgrade kit ($29) - it moves the solution through all the buckets thus maintaining the same pH and ppm in all of the buckets. I assure you that the further you go in your grow the more the pH and ppm will vary in each bucket - plus you only have to check the pH and ppm in the controller and add what you need - it will move the solution through the other buckets. I usually have to add 5ml of pH down every couple of days to maintain a pH in the high 5's. Emptying 4 of the buckets into a container and adjusting the pH then pouring it back through the hydroton is senseless. You shouldn't have to spend more than a few minutes a day on your plants and an hour or so once a week when you change the nute solution - very simple.

Thanks a lot for the quick replies, guys. I forgot to mention, I'm using distilled water with a neutral pH. And I did calibrate the pH meter 3 days ago, and am cleaning it carefully after each use and storing it in buffer solution.

MickFoster said:

I wouldn't pack it in the waterfarms yet - they grow incredible plants. I have done soil, hempy buckets and waterfarms and the waterfarms blow them away. If you are using new hydroton it will significantly raise the pH every day for awhile but will eventually stabilize - just keep adjusting it. I know that people say hydroton is inert and pH neutral but trust me it isn't - it will raise your pH. I did an experiment a few years ago because I had the same problems with the waterfarms and when I asked for advice people told me it couldn't be the hydroton. I took a 5.5 pH stabilized weak nute solution and put half in a glass by itself and put the other half in a glass with some hydroton pebbles - in 24 hrs the glass with the hydroton had jumped to 6.3 pH.

Click to expand...

You know, I'll bet you're on to something there. Last week, I checked the pH of about a half gallon of nute solution that was left over in the mixing bucket about 24 hours later, and it was unchanged. The nute solution in the modules was almost 7. I ruled out the hydroton, and assumed that the problem had something to do with whatever chemical process was occuring within the modules. I should have looked at it a little more deeply and tried the experiment you used.

The next grow, I'm putting the controller back in the system, along with a recirculator pump. The reason I took the controller out of the loop was to save space in the growing area - the flowering room is small, and by taking that out I had room for an additional row of 4 modules, increasing yield by 50%. I was assuming I'd only have to adjust pH a couple of times a week, so I decided this was a worthwhile tradeoff.

Now that I've been doing it a couple of weeks, i see that I can have my cake and eat it too by leaving the third set of modules in the flowering room, settting up the controller just outside the flowering room, and drilling a couple of holes through the wall to run the hoses. That should also help keep temperatures down in the nute mix by transferring heat out of the flowering chamber and into the 55-degree basement.

Thanks again, everyone. I'll try that experiment with the hydroton today, and see if that confirms it.

Well, to update - it's apparently not the hydroton. I did an Official Scientific Test. I dipped out 3 plastic cups of the nute mix, and checked the pH on all three. pH reaqd 4.8. I left 1 cup alone, put a hgandful of hydroton in another, and a handful of Hydromite or somethig like that in the 3rd. Checked them today, and the nute-only cup still read 4.8, while both the other cups read 5.2. Meanwhile, the nutes in the growing modules had, once again, skyrocketed from 4.8 to 7.4, as they do every day.

Has anyone got any idea what could be causing this? The only difference between the nutes in the growing modules and the nutes in the cups is that one batch spent 24 hours in the growing system, and the other batch spent 24 hours outside the grow room. Yet the nute mix in the modules jumped well over a point and a half in pH, and the other batch went up less than a half a point, whereas the cup of nutes that had no hydroton at all maintained a constant pH. This seems really weird. Anyone have any ideas?

Ok I'm a noob so take that into account before you all start yelling at me, but I had the same problem with a waterfarm bucket(just one). I was also using GH nutes, RO water and going through GH PH Down like crazy. The only thing that worked for me was I got thier Hardwater micro and split it with the regular ie 50/50 mix of the micro. After that my PH would slightly drop over 48 to 72 hours and I foud it easier to adjust with a little baking soda than all that PH down. On another note I do think it has something to do with all the O2 the water farm produces, had the same problem with my flood tables until I took the airstones out of the res now my PH holds for a good 3-4 days(still using 50/50 mix on the micro) Don't know if this helps but it did me

Good Luck