Leaves randomly yellowing

[desertxvenom]

This is my Northern Lights Autoflower which is 66 days old from seed.
Medium - Biobizz light mix,
Feeding schedule:
4ml Bio Grow
4Bl Bio Bloom
0.8ml calmag per litre of water
Watering with 2l of water every 2-3 days.
I noticed the bottom leaves turning yellow but i thought that due to them being older and getting less light that was normal but today when i went to water i noticed more leaves turning yellow and they seem to be doing that in random places around the plant
I’ve also attached a photo of the main cola so you get an idea of how far along it is

 

[kfigerm]

don't know the dosage of the nutes, but looks like they want more of everything, esp. K.
Check if PH of runoff is OK, but I think taht could be fine. go for mid flower mix, I'd say.

 

[desertxvenom]

don't know the dosage of the nutes, but looks like they want more of everything, esp. K.
Check if PH of runoff is OK, but I think taht could be fine. go for mid flower mix, I'd say.

Cheers for the help.
I’ll up the nutes and see if that has any effect

 

[DCLXVI]

What pH are you watering into the soil? I ran BBLM a couple times, wasn't very good at it, but! 6.3 is the ideal pH for water in that soil.

 

[desertxvenom]

What pH are you watering into the soil? I ran BBLM a couple times, wasn't very good at it, but! 6.3 is the ideal pH for water in that soil.

I measured it and it’s an 8 pH going in.
I am going to order some PH down but i wasn’t sure as i read that good soil will decrease the PH to the required level itself

 

[kfigerm]

...just until the buffering is gone.
A PH swing in soil happens (fast) if nutes are out of balance and/or overwatering. Most often happens in stretch or beginnig of flowering.
There's a log goin on in the soil, especially when feeding mineral nutes. Bio may feed the soil, mineral feed the plant.
There's all the feed depending on the PH and you shouldn't rely on the soil. Even "good" soil gets out of balance, if you do things wrong.
It's not just the PH of the water you pour in, there's more, but it's essential to keep all on track and to be able to react and to rule things out.
get the tools and go check the runoff properly and then look for a way to act. It's a big difference in the measures to take if PH is in range or not.
EC meter and PH meter are cheap and are "the basic tools" you may want.

 

[Bob's Auto's]

I would wait with adding more nutrients to the mix until you've got your pH figured out. Unless you are working with a "don't adjust your pH" nutrient line, pH is the single most important thing to get under control.
A couple of tips:

• It's easier to adjust and keep larger quantities of water then it is with smaller amounts. So try to install a 50L/13gallon tank/bottle (to stoned to find the right word...) and fill that up with water. Add an airstone and aerate for 24 hours. Add your acid (in nearly all cases) in small amounts (start with 5ml) and measure how much acid you use every time. When you've got the pH at the value you want (in your case 6.5'ish) leave it in there for another day or so and measure again. You'll notice that the pH has changed and you'll have to add some extra acid in there. Again add this to the total amount of acid used. Now your pH is at the value you want and stable at that value. You could measure the next day and adjust again, but then we're just talking 0.01 changes...
• Buy a decent quality pH meter/pen. The opinions differ depending on who you ask, but for about 40$ you should have a nice (beginners) model.
• Use syringes to measure liquids and a scale to weigh dry nutrients. Put spoons, cups and other stuff in the kitchen where it belongs.
• You can use pH down or pH mini for a swimming pool provided the product is based on Sulfuric Acid, nothing else!! If you can't read a label don't mess about and go to a growshop. They can help you out with everything

 

[DCLXVI]

I measured it and it’s an 8 pH going in.
I am going to order some PH down but i wasn’t sure as i read that good soil will decrease the PH to the required level itself

That is true for soil which has been built for that type of grow. The BioBizz soil is fairly inert but does have enough nutrients for the first few weeks. It will need pH adjustments.

 

[desertxvenom]

...just until the buffering is gone.
A PH swing in soil happens (fast) if nutes are out of balance and/or overwatering. Most often happens in stretch or beginnig of flowering.
There's a log goin on in the soil, especially when feeding mineral nutes. Bio may feed the soil, mineral feed the plant.
There's all the feed depending on the PH and you shouldn't rely on the soil. Even "good" soil gets out of balance, if you do things wrong.
It's not just the PH of the water you pour in, there's more, but it's essential to keep all on track and to be able to react and to rule things out.
get the tools and go check the runoff properly and then look for a way to act. It's a big difference in the measures to take if PH is in range or not.
EC meter and PH meter are cheap and are "the basic tools" you may want.

I would wait with adding more nutrients to the mix until you've got your pH figured out. Unless you are working with a "don't adjust your pH" nutrient line, pH is the single most important thing to get under control.
A couple of tips:

• It's easier to adjust and keep larger quantities of water then it is with smaller amounts. So try to install a 50L/13gallon tank/bottle (to stoned to find the right word...) and fill that up with water. Add an airstone and aerate for 24 hours. Add your acid (in nearly all cases) in small amounts (start with 5ml) and measure how much acid you use every time. When you've got the pH at the value you want (in your case 6.5'ish) leave it in there for another day or so and measure again. You'll notice that the pH has changed and you'll have to add some extra acid in there. Again add this to the total amount of acid used. Now your pH is at the value you want and stable at that value. You could measure the next day and adjust again, but then we're just talking 0.01 changes...
• Buy a decent quality pH meter/pen. The opinions differ depending on who you ask, but for about 40$ you should have a nice (beginners) model.
• Use syringes to measure liquids and a scale to weigh dry nutrients. Put spoons, cups and other stuff in the kitchen where it belongs.
• You can use pH down or pH mini for a swimming pool provided the product is based on Sulfuric Acid, nothing else!! If you can't read a label don't mess about and go to a growshop. They can help you out with everything

That is true for soil which has been built for that type of grow. The BioBizz soil is fairly inert but does have enough nutrients for the first few weeks. It will need pH adjustments.

Thank you all for your input
I did get a PH meter (one of them cheap ones that don’t need batteries) but apparently they should be avoided due to them being inaccurate.
I’ll order some ph down and since i’m using biobizz nutes i thought that i’ll give the biobizz ph down a shot.

 

[DCLXVI]

I have a Milwaukee Instruments pH600aq pen. It's about $20-25 and you can get it off of Amazon. I've used mine for 2 years at this point, changed batteries once, and it still works very well. You will also need to get calibration fluid and storage solution.

A pH meter is a good place to spend some extra money on a good one but when you're starting out it may seem like you are constantly buying stuff. I found the Milwaukee to be better than the extremely cheap $10 meters without breaking the bank. It does have some break in time where you will need to calibrate it once a week. After that it's held it's calibration and I test/adjust it once a month.

Milwaukee pH600AQ Digital pH Pen

The Milwaukee Instruments compact pH pen tester is often used to help maintain pools and aquariums as well as improve results for growers and quality in a range of food and beverage uses.

milwaukeeinstruments.com