Why has my Ph droped?

[cwesto]

I grow in soil, righ now i am in 2 gal. pots. I have 6 plants that are about 25-26 days through veg. I have been using only growbig mixed with rested tap water. I started at 1tsp/gal after 1 week of veg have worked my way up to 2 tsp/gal. My plants look healthy and all, but today when i watered and tested runoff Ph almost all of my 6 plants tested at around a PH of 5.... Why is my Ph droping?? I was thinking possible salt build up, I heard that FoxFarm products tend to create alot of salt..

I thought of something. The runoff itself looked a little brown or orange i thought, Maybee that along with the color of the Ph testing solution showed a lower Ph that it actually was... does that sound possible or logical at all??

[whatsthatsmell]

Salt buildup from your nutes will cause your soil pH to drop. To fix this problem you should flush your plants with double the amount of water as there is soil, so if your in a 2 gallon pot your going to flush your plant with 4 gallons of water. The 4 gallons of pH adjusted water will remove alot of that salt in your soil, then you can test your soil run off again. You should be around the correct range, if not, keep flushing until you reach that magic number. IF you do not flush your plant, you will end up in a lockout and if left unattended could take you over a month to get out of.

Hope that helps.

[stinkyattic]

I'll betcha that your potting soil is peat-based and the lime buffer added at the packaging facility is used up.

What brand and type of soil is it?

Ergh I hate peat moss....

[organic_sourdiesel]

I'm using promix HP. I've only watered it twice... once with ph 6.3 for planting, then with ph 6.3, ppm 600 for the first feeding. I'm using botanicare. The runoff tests 4 days later came out at ph 5 and from 1000-1600 ppm! This is just nuts! I don't understand.

The HP is brand new, so the lime should still be in there... I didn't add any more dolomite, which could have been a mistake...

I've never seen such a drop. I'm flushing now, and I've only fed once. This is not cool. My leaf fringes are curled up, and there are some twisted leaves. Oh, and some of the lower fan leaves have rust spots.

I have two posts in the indoor growing section, explaining more about my setup and situation.

I'd appreciate any advice...
bless

[stinkyattic]

Promix is peat.
Never heard of the HP; it's the BX that cannabis growers use, so I looked it up... seems it's pre-ferted as well... 'micronutrients and macronutrients' are listed as components. pH range is listed from 5.5-6.5. That's quite a window... yikes.
You gotta get them into better medium.
That is only going to get worse.
http://www.hort.purdue.edu/hort/facilities/downloads/proMixHP.pdf
I hate peat...
Flush with water at 7.5-8.0. Find a new soil. Repot at your earliest convenience.

[Weedhound]

You say your leaf edges are curled up? Got a pic? I'd love to see if possible...

[Sjapp]

ha sorry... i'm embarrassed. what are pH levels? all i know is that pH=-logH from my math class...

[cwesto]

SA, I am using a mixture of 3:1 ocean forest to perlite, with a layer of hydroton covering the soil to maintain moisture. That is my mix ans soil, I didnt notice peat moss on the back of the bag when i bought, but i could be wrong.

The thing is my plants look generaly healthy, heres some check out my new pics onmy grow log, which u can find in my signature..

[growbe]

The growing concensus is that most are using HP and not BX anymore due to the lack of perlite in bx and the added vermiculite. Most promix growers are adding 1 tbls of lime to to 1 gal of HP, and about 20 percent more perlite. HP also has MYCORISE.
I have seen side by side grows of bx and hp, clones nothing added at all and the hp grows better plants.
Optimum ph in promix is 5.6 to 6.2 You should adjust nutrient solution ph to about 5.8 to 6 after everything is added. This ph seems low but is necessary to make iron, manganese, zinc, copper, boron, and phosphorus available to the plant. At higher ph, these become less avail. to the plant.
Biggest problem with the promix thing is that the lime charge that provides the plant calcium and magnesium is going to run out after repeated waterings. I doubt the foxfarm nutes have alot of cal mag. I would say after a couple weeks, calcium and magnesium should be added at a low rate to water. 1/4 teaspoon of powdered gypsum or calcium nitrate + 1/4 teaspoon epsom salts per gallon of water can be used to do this. Add everytime if def. occurs such as mag def with green veins on bottom leaves but geting yellow.
If you are going to keep them in promix, keep it wet and feed every other time with small amounts of ferts.
BUT it looks like the damage is done.

[organic_sourdiesel]

Well, I took some ph/ppm tests and half of my garden read around 5.0ph/900-1000ppm, and the other half read 5.3ph/600-700ppm. The first half didn't get flushed as much as the second did. So last night I flushed them all with ph7.6 water. My res and # of plants only allows for 1 litre of water per plant, so that's all I can do, unless I use tap water that hasn't sit for 24hours... The tests I did today were only a little higher in ph, so I suppose I need to flush one more time with a high ph to try and get them back into a nice range.

The plants are looking hungry (they are pale in the new growth, and have rust spots on the older growth), and I'm worried about this progressing too far if they don't get food for another 4 days (time it will take them to dry out again after this flush). I'm sure there is still food in there, but I'm worried about the ratios after flushing like this... Maybe I'll flush them with a mild dose of calMax, or bloom/veg... I was thinking it would be a good idea to foliar feed them with a weak solution of half bloom and half veg (I'm in transition as of Monday). I am using botanicare pro veg and pro bloom soil. Does this sound like a good idea?



Optimum ph in promix is 5.6 to 6.2 You should adjust nutrient solution ph to about 5.8 to 6 after everything is added. This ph seems low but is necessary to make iron, manganese, zinc, copper, boron, and phosphorus available to the plant. At higher ph, these become less avail. to the plant.

Although stinkyattik suggested it, it is not feasible to repot my current grow into new soil now... That would be too much more of a cost. I'm guessing that I will have to feed with a higher ph to allow for the drop that seems to occur... A store owner in my town said to always feed with 6.8.... seems about right, as the ph in my runoff is always in the low 5s after 6.3 went in, for the last 3 or 4 crops. I wish I had used dolomite lime this time, and more of it in the past... I forgot that GH nutes are ph buffered... Botanicare seems to lower the ph in the peat in a MAJOR way.

I don't have a cam to show pics of my leaf fringes that are curled up. By fringes, I'm referring to the sides of the leaves...

As always, I appreciate the advice...
I'm considering switching back to buckets...

peace

[cwesto]

SA, do u think that if i implemented bush doctor sledgehammer by foxfarm into my feeding schedule it would take care of this problem??

[whatsthatsmell]

you can use tap water that hasnt been sitting out....i do all the time and have no problems (well currently, i did before because i followed the label on some nutes and burned them). Your really not doing all that much by leaving it sit out, yes, it will bring the pH down some, but its not gonna be enough to worry about. You need to keep flushing those plants until the water coming out of the bottom of the plant reads 6.5 - 6.9, after that is completed you plants will return the love in about 24 - 48 hours (you should see a difference that quick in soil) You dont HAVE to repot, it is recommended, but not a necessity, you will just have to remember to watch that soil pH closely.

[organic_sourdiesel]

Well, the reason I always let my tap water sit overnight with bubblers is to get rid of the chlorine that the city puts in it, not for the ph to move...

I mentioned in another post that I have had lockout/salt buildup before, and once I used the hose to keep flushing my 3 gallon pots, as it took amazing amounts of water to bring the ph up to 6.0. Even after doing this, my plants were deficient and never recovered, resulting in them finishing early by 3 weeks. This happened a second and third time. (sheesh!) The second time, I flushed, then with the pots still soaked, fed them a medium strength mixture. This did not work either. They kept getting more and more pale with lots of yellow dying leaves, and the plants finished early by about 2 weeks. The last time when it happened (I'm always putting in ph6.3/6.4 btw), I flushed them and then fed them, they were still yellowing, then I gave them cal-max, and they greened up again and the leaves were perfect until the end. Perfectly straight and a nice medium green. So it worked, but they were still bolting (finishing) already, and finished a couple weeks early. Every time this bolting has happened, the herb has been top quality, but the buds small, and plenty of "popcorn" bud... I've only been getting like 1/2 Lb per 1000watts.

So I'm worried about flushing away the only nutes left in the soil, but I'm also worried about lockout setting in. I'm thinking that it just might be a good idea to flush them hard tonight until the runoff is at least 6.0 or a bit higher. Then it will take about 4-5 days for them to dry out before I can get food to them, so this might contribute further to any kind of deficiency. They are looking paler in all of the new growth now... As I asked before, does anyone think it is a good idea to foliar feed them with this:
pbp grow 2.5mL/gal
pbp bloom soil 2.5mL/gal
should I add some calmax?
this is about 200 or 250 ppm (don't remember exactly, but around there)
I have this solution ready in my sprayer. I made it weak as the plants were overfed initially, but they really do look like they are lacking a bit now... I was going to apply it right before the lights turn off. good idea?

After all this, when I get back to regular feeding, I'm feeling that (botanicare nutes which they say to use every watering), I should only feed at 1/2 strength, and maybe only every other watering. Thoughts on this? Perhaps even less? their recipe goes up to like 25-30mL/g, and this seems way to high for diesel, which is pretty sensitive, being sativa predom...

My setup:
- 1000 watt hps x 8, four of which are air cooled
- lights are 18" above plants on average
- 78 1 gallon pots on four tables
- 3 oscillating fans
- drain tables on sawhorses with pond liner and drain lines
- room temps: day(light): 75-80 night(dark): 70-73
- room %RH: low... 30-35 (this is not the cause of my leaf fringes curling up. That has never happened before, and I grow in the summer and winter. I've been in this house for 4 years)
- large carbon can on exhaust. exhaust is on a switch, which is connected to a motor control so the fan switches to lower speed at night and the intake turns off
- 100 gallon res with four air stones and two aquarium heaters
- tri-meter ph/ppm/temp (the best, IMHO) properly calibrated
- 2 1500 watt heaters for dark time
- 400watt MH with 4 young mothers
- 2 sulfer burners in case powdery mildew sets in (then use 1 hour per day, which works great)
- 1 6 burner CO2 generator, which runs on a standard barbecue propane tank (not used until week 2 of bloom)
- organic sourdiesel week 1 bloom.

I have a very nice setup and perfect conditions. Perhaps a little more humidity would be nice, but it is not causing any problems. I have been growing for like 8 years, but am fairly new to soilless, and it has been giving me problems. We were having trouble keeping water temps down for the bucket hydro system, and switched to soil for the "forgiveness" of it. Just seems that all the nute companies instruct you to overfeed. I've used
GH, Advanced, back to GH and now am with Botanicare (I want to be organic). This seems to be the case whether we keep our girls small in 1gals or go bigger in 3gals. One of the best rounds with the diesel was when ever other watering, we were flushing 6 gals for every plant. This was WAY too much work. I've discovered the key is to not soak all the soil when you feed. Just a small bit that only gets the top wet, then twice as much water on the next irrigation.

Well... that's a lot for now. I'm hoping to give a complete picture of my setup and problems and experience. Perhaps I should start a log...

one love

Here is my first thread:
http://boards.cannabis.com/indoor-growing/142020-switch-botanicare-gh-adv-advice-please.html

[stinkyattic]

The last step in the flushing process, if you're not harvesting within the next week or so, should be a heavy watering with a nute solution that is pH'd and at about 1/4 of what the manufacturer recommends. That should avoid deficiencies that were caused by removing the available nutes from the soil.

[saltypimp]

hey cwesto -

You r problem is usinf pro mix "HP"...it has a range of ph, i believe, 5.3 to 5.7 out of the container it was sold in (somewhere around, not #, but forgot) use the pro mix "BX"... it has a range of 5.5 to 6.3 out of the box i believe...

just add some extra perlite and you got yourself some "HP" using "BX"... you should be adding extra perlite anyweays so why not just get "Pro mix BX" and add some perlite, and what do you konw, you got some pro mix HP ( with added vermilculite, dont like this, but its better than havinf ph issues... never had problems with BX, but with HP had promblems.... hope this helps!

( i rerad this off a fourm, and tested myself what the soil ph waas on these hp and bx right out of the paltic containers they were housed in)

[saltypimp]

out of the containers (brand new) runoff ph:

"HP - 5.2-6.2 PH"

"BX - 5.5-6.5 PH"

Use BX, much easier to use and control ph...for me at least