Mag Def? and Soil Ph?

Good morning RIU

It looks like my plant has started to show some signs distress. I am very confused as it looks like Mag deficiency, which would mean soil PH was too high. Yet when I PH'd the run off it was at 5.0; I used my soil PH tester and it said 7. So I am confused. If you can confirm it is a mag def then what do I do to up the soil PH, feed it again as the nutes are very acidic and the salt will make the soil more acidic? May do full str feed? Or is it something else and I need a different solution.

I put pictures of the symptoms and the PH tests and also answered some other questions below. If you need more informaiton about what was done to the plants and when they are all in my detailed grow journal, but i think pics could tell the story.

Soil Growers:
1. Are you growing from seed or clones? - Seeds
2. How old are your plants? 32 days from sprout
3. How tall are your plants? 11 inches
4. What size containers are they planted in? 3 gallon smart pot
5. What is your soil mix? FFOF
6. How often do you water and what type of water do you use? Water when needed... I use the lift method to know when i need to water. I used filtered tap water PHed to 6.0
7. What is the pH of your water? 6.0
8. What kind of fertilizer do you use and what is its NPK ratio? I use fox farm trio, only fed 2 times last time was 50% strt which was 3 tea spoons of big bloom and 1 tea spoon of grow big in 1 gallon of water as per week 4 of the directions.
9. Do you foliar feed or spray your plants with anything? no, when i water with non nutes I do use watering can which does put water on the leaves. I use a funnel apparatus when I feed to reduce splash up.
10. What kind of lights do you use and how many watts combined? CFL 230watts @ 3 to 1 ratio of 2700k to 6500k
11. How close are your lights to the plants? 2 - 4 inches
12. What size is your grow space in square feet? 6.5 sq ft
13. What is the temperature and humidity in your grow space? Max 84 low 70 @ 34 to 48% humidity; but increased air flow today so should not hit 84 again, I would say max 82 at canopy. before it may have hit higher than 84 at canopy
14. What is the pH of the soil? no idea, used a soil test shows 7.0 yet PHed run off at same time and it shows 5.0 (see pic)
15. Have you noticed any insect activity in your grow space? nope
16. How much experience do you have growing? 32 days, this is my first grow




The above yellow parts of the leaf are extremely dry and brittle, as you can see in pic all the way to left one even cracked from touch. the problem is wide spread amongst the lower canopy but not prevelent amongst the upper (although few looks like starting signs).

Thanks in advance for help

- Face

watering with about 2 gallons of fresh water as a sort of mini flush and ph'd the run off again it was about 6.0

So not really sure what the problem is as that is good ph for soil i think

Soil about 6.5 I believe is best for absorption of all nutes brotha I think 6 Is closer to maybe coco...

If your tap water is soft (has a low ppm, little Ca and Mg) you need to add cal-mag before you add your nutrients.

Nutrients will lower pH of soft water drastically, calcium helps buffer the acid. It also provides the plants with essential nutrients.

sometimes people let the medium dry out too much, causing the nutrients in the water to dry up and crystallize on the roots. its good you gave it a little leeching to prevents salt build up but you have had it in that soil for a month so i'd just start introducing Cal-Mag as stated above

Mcwhippin420 said:

Soil about 6.5 I believe is best for absorption of all nutes brotha I think 6 Is closer to maybe coco...

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Bingo , we have a winner . Soil should be at 6.5-7.0 with 6.8 being the most ideal . I have typed this a thousand times and now a thousand and one , FFOF Soil is not the best for pH stability due to a few things but the biggest reason is that they only use oyster shell for buffering and I do not think there is enough from the get go . Eventually with aging this buffer is rendered worthless and often this happens before purchase during long term storage .

Sad Face , turn that frown upside down my friend .
Your lil girl actually looks a bit hungry all the way around and with a little more feeding and pH adjustment I think you and she will fair just fine . Perhaps next time add some Dolomite lime while potting .

Just another FYI , the meter your using to check your soil is probably worthless as most soil meters are junk and they do not really work unless you spend a fair bit of cash on a professional model such as a Kelway or Blue Lab soil meter , there are some others worth mentioning as well but stay away from the rapid test and those like it .

Nizza said:

sometimes people let the medium dry out too much, causing the nutrients in the water to dry up and crystallize on the roots. its good you gave it a little leeching to prevents salt build up but you have had it in that soil for a month so i'd just start introducing Cal-Mag as stated above

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And you are right , the soil does look a bit excessively dry .

i think the fox farm ocean forest thing is due to them outsourcing for ingredients from blowing up so quick, some people are strongly for ff soil because it is supposed to be ~ 6.5 ph but i found mine was way way way lower.. i never even used ph up or down cause my tap water was 7.1 with 110 ppm. just added a 1/4 tsp /gal of dyna grow and that would bring it to 7 or 6.8 depending if i added a lil extra.
after it being in the pot for a month i flushed thoroughly to buffer the soil to 7 and kept up with my routine

hey dude i had the very same problem like your plant in the 2nd pic . I checked the ph and was about 5!!!!!! after i had it corrected she got so better in a week time

Thanks Guys for all your replies! yeah I think i did let the soil dry out too much, but i think i had the start of a cal mag def before as well.

So followed all of you suggestions and ordered some cal mag, so i will use that in my next feeding in addition to my other nutes. Thank you all for all your advice and words of encouragement!

ProfessorPotSnob said:

Sad Face , turn that frown upside down my friend .
Your lil girl actually looks a bit hungry all the way around and with a little more feeding and pH adjustment I think you and she will fair just fine . Perhaps next time add some Dolomite lime while potting .

Just another FYI , the meter your using to check your soil is probably worthless as most soil meters are junk and they do not really work unless you spend a fair bit of cash on a professional model such as a Kelway or Blue Lab soil meter , there are some others worth mentioning as well but stay away from the rapid test and those like it .

Click to expand...

Thanks for the feedback on the rapid test, I may invest in a more expensive ph tester! Thanks again

Nizza said:

i think the fox farm ocean forest thing is due to them outsourcing for ingredients from blowing up so quick, some people are strongly for ff soil because it is supposed to be ~ 6.5 ph but i found mine was way way way lower.. i never even used ph up or down cause my tap water was 7.1 with 110 ppm. just added a 1/4 tsp /gal of dyna grow and that would bring it to 7 or 6.8 depending if i added a lil extra.
after it being in the pot for a month i flushed thoroughly to buffer the soil to 7 and kept up with my routine

Click to expand...

The oyster shells used in FFOF to buffer acids and provide calcium don't last forever. Eventually, they will be washed out or otherwise used up. This is true for any soil. Organic amendments break down over time, release nutrients and need to be replaced.

PROMIX is my fav...pH balanced...you can't fuck it up. As mentioned, I find 6.5 to be the best for soil to avoid lockout...get that shit on lock. Lockout will make you think you have all kinds of problems but it is a simple fix.