PicklesMyMan.... The pH of your water with GIG & SPT, mixed in, is fine.
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When the micro-beasties in the SPT hit a ready food source (in this case your GIG). They multilpy and bio-convert (eat & shit out nutrients in smaller sizes - more easily absorbed by Mary). They do this by making enzymes (acid), all those fancy bottles of enzymes you see in the hydro stores are just the enzymes made by beneficial bacteria.
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So, naturally in the begining your mixed up fertilizer & SPT will travel downwards in pH. After a short time, it bottoms out in the 5 range, then starts going back upwards.
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Your soil, is the best pH buffer out there. No need to add in pH up or pH down products into your fertilizer mix. Just water in your fertilizer mix until you get a slight run off.
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Then two days later, pour some plain water (pH known) through your soil and catch the runoff. Test it's pH. If between 6 and 7, no worries.
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If below 6, simply topdress a alkaline amendment, like high P bat guano, or pulverized dolomite lime. Just a teaspoon total per pot. Always make adjustments in small increments.
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The truth is, the micro-beasties in the soil, tend to self-regulate and level the soil back out in a few days. Provided you aren't consently dropping in very acidic ferts / amendments.
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Most veg ferts tend to be acidic (low pH) most bloom ferts tend to be alkaline (high pH). Using small amounts of one, to balance out the other works well.
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Feeding & Adjusting, should be don.... Low, Slow & Steady...... just like in nature, things can, do & should change over time......
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Hope this helps......
Keep it Real....Organic...... cause chemicals are for cleaning your toilet.....
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