PH Dropping quickly?

You could be right Mr E, my water is well water so there is probably a big difference between that and tap water....you could add an entire bottle of ph down and it would only hold it for a day or two before crawling back up....
I do find that when I first do a res change it takes, as you say, very little but does not stay very stable for the first day or so until I have added more ph down etc, then it seems to stay pretty much where I put it about 48 hours in. Now flowering is a different story with the ph probs

I use baking soda as ph up usually as I only have to use small amounts and it's easier than ph up for me....I doubt I would use it if I had to raise the ph a few points or so....or have to use it often but I have not had any problems using it so far....keep it on hand with my other crowd of bottles. I have found it raises ph kind of slowly over a few minutes so I add a little and then check it a few mins later because the number seems to rise a little more after a min or two. I don't seem to have that particular situation when using ph up/down so just a a heads up.

Well also, the nutes have ph buffers in them, so theoretically a nute solution SHOULD hold it's ph level more stable than plain RO water (or any low ppm water).

Baking soda not only raises ph, it supposedly also has a buffering effect. So it COULD be a possible better choice for me (or supplement) since my RO water seems to be very very unstable.

I had to PH Up my res twice today in fact, and "chasing ph" is suppose to be bad for the plants. After the second dosing, I added about a quart of tap water and the ph rose a couple of more tenths to 6.2. That was 2.5 hours ago and I'm currently looking at 5.9.

Kinda driving me nuts obviously. I have 6 or 7 gallons of plain water on hand, so I may go ahead and mix up a batch of bloom nutes later tonight/tomorrow morning and do a quick drain and fill of the system again. Using some tap water as well.

I've got to get these blooming, they're starting to reek pretty seriously and they're just dying to load up with flowers.. not a good time for me to be goofing around with experiments. But it seems there's no single simple answer, so there we are.

Well I hope latewood or somebody hops in with an answer cause now it's bugging me too!

Well the baking soda SEEMS to have done the trick! I took about half a teaspoon and mixed it with a few tablespoons of water and stirred it a bit and dribbled in a SMALL amount. My ph went up, but it's STAYing up is the important thing.

I believe the article I read on icmag was correct, about it acting as a PH buffer.
It went up quickly, and in fact I'm about to go Down it, lmao.

Res change tomorrow with any ph up adjustments using baking soda and a prayer ;)

Good luck.....update!

PH was exactly the same this morning as it was last night, so it looks like the buffering was what I needed.

Ok, today I did a nearly full res change. I left about 2 gallons in there. I used a slightly weak lucas bloom formula with about 8 gallons of RO water. (I used a formula for 7 gallons when I have a 10 gallon system). Poor plants have been through alot, so I'll see how they behave.

After it had circulated awhile and I adjusted the water level, I ph up'd using a few ml's of the baking soda and water. It took very little, and I'm currently sitting at 5.7PH, 650PPM.

I had trouble with ppms at that number when my plants got to be about 7 weeks old and that's what caused the deficency in my last grow....keep a careful eye....

5.7 and 640ppm now. Looks like so far anyway the ph is nice and stable.

I watch them all day long pretty much, so no trouble there. I had trouble a couple of weeks ago when I had stronger nutes, so I'd rather go light than too strong.

5.8 and 620ppm. Looks like everything is working, my plants are taking up nutes and hopefully well on their way to a healthy flower cycle.
Now we know what to suggest if others ever run into the same problem and have beat their head against the wall trying to figure it out.

Thank god....never knew the baking soda I was using did that....

5.7 and 660 today. I topped up with nuted solution. They're drinking it up really well now :)

Weedhound, it's possible that your water is buffering PH already too. Here is a great article on water, and where I finally got the idea to try baking soda (never would have occured to me, as the common good advice is always stick with the professional ph adjusters): http://www.icmag.com/ic/showthread.php?t=23357

My plants are bursting with fresh growth now.

Well I read the water article Mr E but there are still some things I don't get....all those ferts etc are supposed to already have ph buffers in them. Why aren't they working for you??!! I did notice however that when I mix a new batch of ferts the ph is usually low and I bring it up with baking soda before I do a res change so perhaps I've just plain been way ahead of you the whole time.....the last few times I have done res changes I have not had to raise my ph first and now thinking about it I realize that the ph is not staying as stable at first as it was but settles down pretty well after I adjust it with ph down for the first time. (Always goes up.... never down so ha)

You may have been ahead of the game (only way to know I suppose is try store bought PH Up if you dare and try, lol), or your basic water chemistry may include sufficient buffers already. You'd need much more than a basic PH probe to test such actual numbers I think.

But also, my WORST case of ph dropping like crazy was when I was using plain RO water, no nutes at all. And it was dropping full points in a day (6 to 5 etc).

I'm glad to say though that now my PH is absolutely rock steady! Seriously like a miracle.

I think the bottom line really is that if you see CRAZY swings where you have to adjust the heck out of it one way or the other constantly, you very well may simply lack enough PH buffering in your *water* (regardless of nute brands), so a small bit of sodium bicorbonate could very well help stabalize it.

I've flipped over to 12/12 starting today, and replaced my MH with my HPS. These plants are going to be twice as big as I'd wanted them to be, but I can hope for a quick flower cycle I guess.

Yeah more buds, more trichomes what a shame :D The fun part is unprying all the branches and leaves that grew up into the light and ceiling beams.
Sure glad your grow is back on track!

lol true. I'll have more harvest, but boy is it ever gonna stink in there.. Plus the light wont penetrate as much, but I'm supplementing it with side lights. I had to drag the tub 6 more inches from the wall because some leaves were touching this morning.

Since 2 plants are in only a 10 gallon tub, they're shoving away from/against each other, with leaves and branches all mashing together. The top looks almost like a scrog with no screen, lol. Not really, but bushy bushy. This strain would definitely be excellent for outdoor. It'd be round.

PH is still rock solid wherever I set it. The issue I'm working to keep up with now is topping up the res, because they're drinking/eating like pigs! LOL

Oh, I'd forgot that you asked for pics.

Dec 2nd on left, Jan 2nd on right (best I could do with main light on and POS camera). No training or topping at all.

Ph problems or not--good job! Is the second pic one plant or two? It looks just fine for two plants but quite the beast if it's only one.

It's both plants in the same little container still. Camera sucks, but there's branch tops everywhere and they're just as full on the opposite side, but I can't get back there, lol.

I rigged up a little shelf for my fan so I can remove a little cabinet that you can almost see in there, to give them the full 5 foot width to grow into.

I think this strain (alien's NLX) would scrog really well. I'm anxious to see how they fill out. Hope they can handle the weight they're going to be carrying.

PH still completely fine. All I've needed to do still is up it slightly with baking soda dissolved in water when I add nutes, or top up the res. making it drop slightly.

Plants are really exploding. At least 2 to 3 inches growth overnight. One branch from the third node is now taller than the plant tops lol. It's opposite branch is quite a bit shorter due to being on the outside edge of the lights "sweet spot" with only supplemental side lighting (and a thick canopy).

Harvest will be quite affected by using only 400 watts (and it's only 2 plants). Next time, short clones thrown into flower quickly, and/or only 1 large plant.

Sounds like it may be time for bigger "light guns"