water 7.5 preventing P absorbtion?

HI bud. 7.5ph ouch. At least, to my ears that doesn't sound all to great for an organic grow. What ph does the soil manufacturer recommend? You should be trying to target that as your runoff measurement. For example: BioBizz recommends 6.2-6.5ph. My tapwater is 7.5. After adding nutrients, the ph of the water is at 7.1. Adding that as is would raise the ph of the soil. If I want to keep the soil no higher than 6.5, I have to PH Down the mixture to under 6.5 else the ph of the soil will raise. Secondly and lastly, what does the supplier of the nutrients and microbes recommend? Some work best at 6.2 while others work better at 6.5-8. In my case, the ph cannot exceed 7 due to the live worms in the soil. The microbes I use work best between 6.2-5. The nutrients also, 6.2-5. That's where I'd start. Hope this helps :)

How come you don't just lower the PH. Someone told me the other day a few drops of lemon juice or citric acid. Seems organic to me.

7.5 is pretty neutral.Last time I checked mine was several weeks ago and it was 7.Ifnthe soil food web is good the microbes will make the phosphorus available.

Crop growth will gently acidify a medium over time as more and more reactions happen. Phosphorus itself loves 7 not above, not below. In its elemental form its neutral charged, it has special function within plants because of that. Your using organic methods, your soil will have a large capacity for storing cations. (Big3), id guess you have been slightly overfeeding calmag and it's been storing up in the medium replacing other cations as they are used up. 98% minerals are uptake through water solution 2% directly from soil. Most people grow with soil that doesn't have the ability to store charge for later, meaning they need to apply a fresh ratio of fertilizer every feed or as needed. Because your organic it changes things a little, now you have medium thats a battery pack that will store up any excessive salt electrolytes you give her buffering ph from acidification over time. Ph above 7.5 tells you there is an a abundance of the big 3 cations stored in the medium. Ca,Mg and K. Soil with a pH above 7.5 is considered alkaline and can impact plant growth by hindering nutrient uptake and water retention, particularly for acid-loving plants. While not directly related to water retention, alkaline soils due to skewed ratio of Ca,Mg and K can have unexpected effects given how important these 3 are to soil composition and a mediums ability to hold and retain soil structure/retain water. Why is that important.... As the plant performs carbon sequestration it also fills soil with more carbon, carbon is very porous, making soil hold more water capacity. Adequate soil aeration is crucial for efficient phosphorus (P) uptake by plants because it facilitates root metabolism and P movement to root surfaces, while compaction and poor aeration can hinder P absorption. Plant roots require oxygen for energy production (carbohydrate metabolism), which is essential for P uptake. I too often experience a change in soil around week 5 of flower, soil moisture levels play a huge role in sugar signaling complexes and senesceance. If you add more carbon than the plant creates, the medium will become a carbon sink, around 40% of what carbon photosynthesis captures is excreted into the soil through roots to feed microorganisms in form of sugars. This coupled with the dense canopy of flower, the increased workload in less hours, everything is more in flower, given how much more moisture is cycled, I thought maybe it could help to share Insight into P and its relation to aeration/oxygen and the flower periods tendency towards having more moisture. Small creeping problems that buildup over time. Very easy to overlook but you yourself should be able to gauge whether your overwatering, if you have always just blasted her with the same watering then it's possible it could be anoxia as the soil becomes more moisture retaining over time through flower, with the same watering habits it could eventually lead to oxygen deprivation (anoxia) which will greatly restrict P uptake as oxygen is a requirement for the efficent uptake of Phosphorous, given its neutrally charged it uses weak O2 bond as its primary binder. Oxygen or lacktherof is disrupting P, if I was forced to give you a short answer. Hope it🙏 helps with your diagnosis.

An acid of any type can help, but if it's the result of the molecules being slowly released in the substrate, it'll be an uphill battle. So, you can ph-down a bit more than normal to balance it out, but remember pH is a log-scale so don't just 'average' it out. 6 is more acidic than 7.5 is alkaline. The further you go from 7 the more drastic the difference will be. 7.5 should not cause major problems. Maybe, it can exacerbate a small issue, but it may also help you better balance your amendments next time, even so. Anyway, use a dry amendment that is acidic and that can be swapped out for what you currently used etc etc.. think gypsum does that? what's that? calcium and sulfer? Could reduce some other component providing that, retain balance and reduce pH. That soil stuff gets complicated and requires some trial and errorr. The problem is you can't really switch it up midstream once you use the substrate.. just have to reformulate next batch and live with it until then.

Lemon juice or citric acid. GOOD HACK!

If you are using tap water and not using ph up or down you can add some humic acid in the soil to make the soil a little acidic just so it will balance out with the tap water being 7.5 7.5 is pretty normal for tap water

Probably early-stage calcium and maybe magnesium deficiency. Tap water + FloraFlex can sometimes be light on Ca/Mg, especially with Coast of Maine soil, which can buffer strangely. Adding CalMag was a good call – keep that going for a few waterings. Also, watch your watering rhythm – soil likes to breathe between cycles. And just a side note: “dirt” sounds really harsh 😂 – like you took your trash vom the vacuum cleaner😝 Would help to know exactly which Coast of Maine mix you're using – one "dirt" is not equal another "dirt". If it's full of micro activity and potential, humidity and temperature are important to keep in mind. pH should be more or less in range for all above as well in the dirt. Should be a buffered system and if you kick it out of it's zone you need to fix the buffering.

Not gonna lie, I’m not into organics so i had to look this one up lol. But yeah, 7.5 sounds like it could be holding back phosphorus. Even with organic buffers, if your water’s that high and consistent, it might start messing with uptake around mid-flower. Maybe try letting the water sit out a day or two, or drop a bit of lemon juice or citric acid to land it get it to 6.5 to 6.8. Just enough to keep things smoother without hurting the microbes. Hope this helps growmie.