quick pH question

[primitive]

I'm finding I need three times as much pH down to adjust -.2 on the sixth day of a solution recirculating than on the first few days. Is it normal to need substantially more pH adjuster as the solution gets older in an ebb/flow system?

 

[curiouscat420]

if your water gets stale the pH could change a lot... do youhave any bubblers or any sort of water movement in your res??

if you are using tap water this could be a reason for large fluctuation...

what stage of growth are you at??

 

[BuddyLuv]

Are you topping off the res with plain water?

 

[The Hemp Goddess]

Are you adjusting for a .2 drift? It is okay to let your pH drift some to ensure uptake of all the nutrients.

 

[NorCalHal]

What THG said. It is OK to let 'er drift a bit. Constant adjusting before each feeding does more harm then good imo.

 

[curiouscat420]

both of those ol timers got a point... i let my ph drift from 6 to 7 before changing it, but i also do not live with my girls...

near the end of my flowering i started to notice the pH drift more, so i just adjusted it at a lower ph...

THG and NCH are the ones to listen to - im just 'a tryin...

 

[primitive]

Neato, lots of respsonses.

I do use tap water, and I top off with plain tap water, then pH adjust with diluted pH down. I know tap water isn't helping, if anyone can recommend a good RO unit for around $300 let me know

I don't adjust for .2 that was just an example, typically I start with a res. at 5.8 then adjust back down when it gets to ~6.4. But when I mix a new solution, say, ~120ml of pH down will bring a change of 7.1 down to 5.8, but on day six or seven of that solution recirculating, 120ml of pH down may only bring 6.4 down to 6.1. So I'm getting a difference of 1.3 to .3 change from the same amount of pH down over the course of a few days.

I don't have bubblers in my res. I had thought those sort of things were only for DWC; the only movement my solution gets is when it recirculates twice a day, 17 min at noon and 8 min at nine. Res. is 40 gal. So wait, do some people use air stones in an ebb/flow res. just to keep the water moving?

As for stage of growth, I've got one tray at three weeks and one at nine. The ones at nine weeks are shooting up in pH much faster, but the exponentially larger amounts of acid needed to adjust them as time passes seem to be about the same. Though occasionally with the older plants, by the last few days before a res change, I'll add 60ml pH down(diluted into 1/2 gal first), stir it up, wait a half hour, and find no change at all, zero.

And I do calibrate my tester pen before each use.

 

[BuddyLuv]

It is because the nutes are primarily salt based. So if your plants feed and leave the salts behind you have nothing but salt left in the solution. Nutrients themselves will bring your pH down, just do a test sometime for yourself and see. One thing I have seen is that as the plants feed heavier and heavier you will need to use more pH down to compensate. Also why are your diluting your pH down if I may ask?

 

[primitive]

I'm aware nutrients alter pH, I only want to know if needing more adjuster for the same change in pH as the solution gets older is normal, or not. It makes sense to me that more would be needed as the plants get older and use more nutrients, but I don't get why more adjuster is needed as the solution gets used/older

Also why are your diluting your pH down if I may ask?

I dilute it because everything I've read has said to do so. I actually dilute it a lot less than most of what I've read says to do. From the the current issue of Urban Garden magazine, in the article "Opening the Doors of Nutrient PerpHection", "Adding droplets of pH up or down straight from the bottle into your nutrient solution can cause localized chemical reactions that can adversely affect the effectiveness of your nutrients. Make up a solution first (say 20ml per gallon) and use that instead. It's also safer and easier to use in this form." I know I've read this online many places before. I don't bother using a whole gallon of water, but I do measure out no more than 60ml at a time, then top off the 500ml beaker and stir for a second before adding to the res.

 

[primitive]

Dammit, double post. I'm getting server busy messages a lot on this site recently.

 

[TURKEYNECK]

5.5 to 5-8 is ideal, not 5.8-6.4
look at this:
http://www.marijuanapassion.com/forum/attachment.php?attachmentid=1833&d=1141100090

and oxygen in your water is vital..so you def need airstones in the res. ..in the dark.

 

[primitive]

I saw your reply to my continuous read pH meter question, guess I'll have to get airstones. How strong of an air pump, and how many stones do you think a 40 gal. res would need?

Nice chart by the way, grabbed that.

 

[BuddyLuv]

Also a thing to ponder... I let my water sit for about a week before it is used. I have a large shelf with gallon jugs on it that I rotate as needed. What I have found is that even RO water (I have a unit) will at first be about 5.0 but if I let it sit for a week it is about 6.0. Letting it sit stabilizes the pH and my drift is nowhere near as drastic as if I were to use water straight from the RO tap.

 

[TURKEYNECK]

walmart has a duel outlet 40-60gal pump for around $10 the also have 6" airstones for a couple of bucks a piece

 

[primitive]

Also a thing to ponder... I let my water sit for about a week before it is used. I have a large shelf with gallon jugs on it that I rotate as needed. What I have found is that even RO water (I have a unit) will at first be about 5.0 but if I let it sit for a week it is about 6.0. Letting it sit stabilizes the pH and my drift is nowhere near as drastic as if I were to use water straight from the RO tap.

I just got an RO unit, is it normal for the water to come out that low in pH? Today was the first time I opened my bottle of pH UP making a solution.

 

[BuddyLuv]

yeah but it will go up. Did you let the holding tank fill and then empty a few times? The unit I got said to do this to purge the system of anything used to package the membrane filter.

 

[fishcabo]

If you look closely at the nutrient availability chart you will notice that at 5.3 in hydro will not pick up P or Mg well. I run mine at 5.8-6.2 even up to 6.6 once in a while because letting it fluctuate gives the plants better access to ALL the required nutrients. Water General makes a great RO unit 5 stage for about 150 bones on ebay brand new. I got one and it's great.

 

[primitive]

yeah but it will go up. Did you let the holding tank fill and then empty a few times? The unit I got said to do this to purge the system of anything used to package the membrane filter.

Mine just said to run the system for an hour before use, so I did that. I'm getting more confused with pH than I was before, the numbers are jumping around nearly as much with my new meter and RO filter as they were before. Is it normal for pH meters, any pH meter, to jump around -+.3 constantly? If so, ***? How do you work with this? Like, if it's ideal to start a solution in hydro at 5.5, but it's constantly flicking between 5.41, 5.55, 5.67, 5.53, 5.42, 5.39, etc., how do you get it right?

For the RO water I'm going to follow your lead buddyluv, I'm going to get a trash can and let the unit fill that up, then use that water a week later to make the solution. Or would a trash can leach crap into the RO water?

I spent $500 in the hydro shop and am having the same problem now with the toys meant to fix it, this is so frustrating I'm gonna need a weave and dental work from all the hair pulling and teeth grinding over this.

 

[trillions of atoms]

try using gallon distilled water....adding a few bubble wands weighted down in the rezz and that should help alot- the ppm from the tap water and the water sitting stale in the rez is prolly the culprit. what nutes did you say you were using? if the nuteline is cheeper it may not have the needed buffers to keep the ph stable...something to keep in mind.

is the meter calibrated?

 

[pcduck]

My meter would jump all over the place until I calibrated it.