Thanks for commenting and for your kind words!

Awesome, thank you!

Thanks again!

Thank you! So are my viewers it seems!

You're welcome!

Basil is a potassium loving plant. If your solution is high in K, basil can accumulate too much (5-6% in tissue) and the balance can turn towards the pH dropping. Reduce the K in your solution to prevent this problem. An K/N close to 1 works great for these plants.

Yes, it can, in these cases the pH will usually drop due to the production of organic acids by these microbes from the decomposition of root tissue.

@@ScienceinHydroponics Thanks for the answer! That makes sense! Looking forward for more episodes.

I got this from the scientific literature on the matter, it should be cited in the video's description. Let me know if you cannot find it.

I'm actually having a similar issue in pro mix HP (mostly peat moss and perlite with lime and wetting agent) I noticed my runoff pH was high a week or so ago. My input the whole grow up until then was 5.9 or so. After noticing the runoff was approaching 7 I stopped adding the sodium hydroxide as a pH down for 5 or so days. Without it my salts bring my pH down very low, 3.5 low. I fed the plants this for a few days and my runoff is still pH 6.9. I noticed some edges starting to brown on some of my plants already so I think I'm going to adjust the input pH back to 5.9 and try and figure out another reason this could be happening. I am using purecal as my calcium nitrate and it doesn't have any ammonium in it so that might be a possibility. I'm also not sure if salt buildup in the media being flushed out at a new irrigation could affect the pH of the runoff. This is the second grow this has happened though. Could it also be due to the plant taking up more anions than cations? I would have guessed my extremely low pH would have at least made a difference with the runoff but it hasn't really done much in days and if anything the plants have gone downhill since lol

You should never feed lower than a 5.2, even that should only be done for brief periods and 5.5 should be considered the minimum for longer term feeding. High pH in the media can be caused by improperly balanced solutions - that push anion uptake even higher than necessary and do not have ammonium counter balance - or by media that has been improperly amended with a base (for example calcium carbonate). You need to review your formulation and add around 20% of your total N as ammonium, up to around week 3 of flower. You should also review the composition of the coco you're using and ensure that it contains no base additions (runoff of the coco with nutrient at 5.5 and without plants, should be below 6).

Peat moss contains lime to compensate for the low pH of the peat moss media. This makes it problematic in terms of controlling the chemistry of the media. Even if you feed very acidic formulations, the amendment + plant uptake is going to normalize the pH towards 7 if too much of it is present. In any case, ammonium free formulations will exacerbate the problem of high nitrate uptake, adding to that the problem with the lime and you will get uncontrollable up swings in pH. Do not feed lower than 5.5, as contact with very acidic solution can kill plant roots. You need to properly balance your solution with enough ammonium, avoid high EC feeds (keep inputs below 2.2 mS/cm) to avoid excessive swings and use a peat moss media that has a mild lime amendment. Peat moss does not work well with high EC feeds, because of how this plays with the amendments within the media. Improperly buffered peat can also be exceedingly high in pH at the start and then become extremely low pH once the amendment runs out. Using coco, perlite or rockwool would be less complicated in terms of controlling the media chemistry.

@@ScienceinHydroponics Appreciate you taking the time to write out a detailed response. A lot of what you said makes a lot of sense. I had no idea about the very low pH burning roots (should be obvious now that I think about it) so I had to learn the hard way. I went down to my grow yesterday and saw bananas everywhere. Might be a restart unfortunately. I've been using pro mix HP mostly because it's much cheaper where I'm at (Canada) compared to other things. At around 25USD for a compressed 3.8cu ft bale that ends up being a lot more once opened. Most bags of coco are around the same for 50l loose which fills up much less. I've always wondered if the high frequency fertigation is messing with the lime though. I will try replacing some of my purecal calcium nitrate for some yara that has a bit of ammonium but I think unfortunately for me the damage has been done. I was reading on your blog awhile ago about a media made with washed sand and rice hulls. It seems pretty appealing to me to try the only potential issue I see is the weight of the media. Is this stuff extremely heavy in general / when it's wet because of the sand? Only thing I'm worried about is it being super heavy / breaking through my thin plastic trays when full of plants. It seems promising how inert it is. And even if it's more expensive than what I'm currently using it's still cheaper than decent coir. I found a bag of rice hulls for about 38USD for 50lb. Washed sand is relatively cheap. I think I might give this media a try if it isn't extremely heavy. I'm starting to lose faith the pro mix I've been using is not always mixed properly or possibly sat on a shelf too long (I think it might have an expiry date printed somewhere) anyways thanks again for the knowledge it definitely helps me become a better grower.

Thanks Dr Dan! I just reworked a mix a few days ago, based on one of the science in hydroponics articles that suggests 80/20 No3/NH4 in the formulation. My question is though, should I cut out all NH4 from my flower mix? Appreciate your help as always.