Question about PH for seedlings

Hi guys,

I have never seen this question asked or answered, so I thought I'd ask since I'm having issues with my ph and how adjusting it is effecting my ppms.

What is the proper ph for seedlings

I germed my tomato seeds last weekend and put them in my waterfarm on Tuesday.

I am using distilled water with a ph of 7 and 0 ppm, when I add ph down, to get between 5.4-5.8 ph, my ppms shoot up to the low 300's. Now a day later my ppms are at 500 and my ph is climbing.

I am using Advanced Nutrients Ph up and down in a waterfarm.

Thanks,

GoLdD

Try a weak mix of hydro nutrients instead of just using plain water. pH can/will be super wacky if there is nothing to buffer it. Your choice of hydro nutrients should be buffered appropriately and your pH adjustments should then be more steady (and require less pH Up/Down).

And just to add, 5.8'ish (ballpark) is fine for seedlings and through flowering in any hydro system.

Thanks Tao,

What about the PPMs though? After I add Ph down my PPMs sky rocket. There is a little burn on the tips of the first set of leaves, I did a res change yesterday with straight distilled water and no Ph adjustment, this morning ph was at 7.3 but I'm worried if I add Ph down it will cause the PPMs to shoot up?

Thanks GoLdD

Yeah you'll have to be careful you aren't going overboard with the nutrient strength to soon (I start at a quarter strength of label for seedlings). The pH down is likely phosphoric acid which will break down into usable phosphorous to the plant - it will increase TDS readings in any case by itself... and with distilled water, even a small amount of nutrient solution should move and hold the pH towards where it needs to be with less being added overall (likely won't have to pH adjust at all). If that makes sense?

Hello. I've used at first some humus with 7-8 ph, but that failed utterly: pre-germined seeds failed to develop and died in this soil. Watering was with tap water, ph 6.5-7. Then, I bought some acidic turba (5-6 ph), pre-germed some other seeds, as well as one from the first batch of seeds, planted them and watered with distilled water (ph 7.89) kept at water temp. This went successfully for 2/2 seeds. Just my 2c.

ValiD said:

Hello. I've used at first some humus with 7-8 ph, but that failed utterly: pre-germined seeds failed to develop and died in this soil. Watering was with tap water, ph 6.5-7. Then, I bought some acidic turba (5-6 ph), pre-germed some other seeds, as well as one from the first batch of seeds, planted them and watered with distilled water (ph 7.89) kept at water temp. This went successfully for 2/2 seeds. Just my 2c.

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Yeah cannabis likes things a little acidic. There are a few differences between hydro and soil when it comes to pH though. With soil growing, the soil itself acts as a buffer. In hydroponics (like the OP is using), there is no buffer except for what is put into the nutrient mix (or if you are using mineral laden tap water)... and hydroponics requires an even more slightly acidic pH range than soil.

here's your answer bro. i found this out on my own, by pure laziness, lol. i "NEVER" ph seedlings, never!!! remember, you ph to allow the plant to be able to take in the proper nutrients. so, since the cotyledons supply the seedling with "all" of it's needs for the first 2 weeks or so, what's the point??? i never have any problems with my little ones.

Hey Guys,

Thanks for the input, I have done a res change since I last posted and have my PPMs under control but. . . . . New problem though, I Ph'ed a new batch of distilled water after adding an 1/6 (1ml for 5 gallons) strength of Roots Excelerator, then let it sit and get stable readings at 5.4 - 5.6 Ph for 12 hours before doing the res change, the new issue is that the Ph has risen over the last 24 hours to 6.8 and I don't know why? Any input is greatly appreciated.

GoLdD

I don't believe RE has any real buffering to it - did you try adding any weak amount of nutrients to the mix?

is that house and garden you're using? if you're still under 2 weeks old, you shouldn't be feeding them anything.

TaoWolf said:

I don't believe RE has any real buffering to it - did you try adding any weak amount of nutrients to the mix?

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Hey Tao thanks for the help , the RE raised the ph slighly .1 at 1ml for 5 gallons. Current PPMs around a 100 (using a blue lab truncheon) My mix was as stated, 5 gallons of distilled water at 0 PPM + 1ml of roots excelerator. Ph'ed after adding the RE, let sit then tweaked it till I hit 5.4, then waited an hour re-checked and tweaked over a few hours till steady at 5.4, then checked 5-6 times over the next 12 hours till I was satisfied that it was stable, then swapped res.

Silky Shagsalot said:

is that house and garden you're using? if you're still under 2 weeks old, you shouldn't be feeding them anything.

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Hey Silky thanks for the help, Yes I'm using House-Garden Roots Excelerator, the Hydro shop guy suggested a 1/4 dose once I had 4 leaves (based on his regiment), I did 1/6. No other nutes, only Ph up/down a drop at a time. They are 1 week old.

Thanks,

GoLdD

their nute calculator (http://www.house-garden.us/nutrient-calculator/) says 1.1 ml per gallon at week one, but i don't start giving them "anything" until 11 or 12 days pass. by then i usually have 3 alternating internodes.

I'm pretty sure RE is just a beneficial microbe additive (I use them from day 1) - I wouldn't get scared into not using it as recommended if so. But I've not used RE specifically so take with a grain of salt.

I'm pretty confident you pH fluctuations will go away once you start them on their basic NPK nutrients. It could easily be something like a rockwool cube or hydroton in your setup that's making the pH rise... not to sound like a broken record, but no buffer equals no steady pH. On the bright side, like someone else said - pH isn't as important if there's nothing for them to actually be feeding on anyway - so it works out.

Hey Silky,

Ya I kind of wish I hadn't added anything, hopefully the low dose doesn't hurt them, do you think that might be why the Ph has risen from 5.4 to 6.8? I am considering adjusting the ph agian but will wait to see what it's like tommorrow.

GoLdD

TaoWolf said:

I'm pretty sure RE is just a beneficial microbe additive (I use them from day 1) - I wouldn't get scared into not using it as recommended if so. But I've not used RE specifically so take with a grain of salt.

I'm pretty confident you pH fluctuations will go away once you start them on their basic NPK nutrients. It could easily be something like a rockwool cube or hydroton in your setup that's making the pH rise... not to sound like a broken record, but no buffer equals no steady pH. On the bright side, like someone else said - pH isn't as important if there's nothing for them to actually be feeding on anyway - so it works out.

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Hey Tao,

My understanding was that it is a microbe additive as well, I put them straight into the hydroton with no other media. I did wash and soak the hydroton over night in distilled water but maybe it wasn't for long enough, hopefully the Ph swings won't hurt the plants development. I am going to take your and Silky's advice and ignore the Ph for the moment and see how it is tommorrow, anything over 7 and I'll adjust the Ph agian.

GoLdD

GoLdD said:

Hey Silky, Ya I kind of wish I hadn't added anything, hopefully the low dose doesn't hurt them, do you think that might be why the Ph has risen from 5.4 to 6.8? I am considering adjusting the ph agian but will wait to see what it's like tommorrow.GoLdD

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i grow in coco, and keep a rez i feed out of. once i set my ph, i don't check it again. if there's nothing in the water, i wouldn't think it would fluctuate. but if you're recirculating, the plant makes demands. i run to waste and avoid that.

GoLdD said:

Hey Tao,

My understanding was that it is a microbe additive as well, I put them straight into the hydroton with no other media. I did wash and soak the hydroton over night in distilled water but maybe it wasn't for long enough, hopefully the Ph swings won't hurt the plants development. I am going to take your and Silky's advice and ignore the Ph for the moment and see how it is tommorrow, anything over 7 and I'll adjust the Ph agian.

GoLdD

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Sounds reasonable to me as long as you aren't having to use a crazy amount of pH down - but with you monitoring EC, I doubt that will be an issue.

Silky Shagsalot said:

i grow in coco, and keep a rez i feed out of. once i set my ph, i don't check it again. if there's nothing in the water, i wouldn't think it would fluctuate. but if you're recirculating, the plant makes demands. i run to waste and avoid that.

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I know it doesn't seem logical at first and it's hard to explain - but the more pure the water, the more pH can fluctuate all over the place. It's like if you took a bottle of clear water and put a drop of yellow food dye in it... that one little drop will appear to have a noticeable impact on the overall color of the water. But if you took a cup of coffee and added just one drop of yellow food dye... it won't have any noticeable difference on the overall color of the coffee because there is so much stuff in the coffee that's already giving it a color. Same principle applies to changing pH; pure water + a drop of something acidic or basic and the overall pH of the water will be impacted greatly. Water with a bunch of stuff in it already... and a drop of something acidic or basic won't have much of an impact (aka the water is buffered).

Hey guys,

UPDATE: pH is at 7.4 and 7.2 for the respective waterfarms, will be adjusting pH shortly! I wish I knew what the problem was

GoLdD