D2G.... I also think that amount of runoff is a waste. Here is how you avoid that waste. Go to Wal-mart and in the isle with flower pots, pick up a clear plastic pot drain pan (sold to keep you indoor potted plants runoff water from ruining the carpet) for each pot you have.
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Before you fill each pot with coco, cut and run two pieces of 1/4 nylon rope (wicks) out the bottom, thru the pot drain holes. Just thread your wick in one hole then out the other side, so you basically make a U shape with each end of the wick sticking out the drain holes a couple of inches. They don't need to be very long, just enough to help drawn in water / nutes.
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That way, you can water / feed only until a slight runoff is seen, then stop. The excess will sit in the drain pan and be wicked back into the coco by the wicks. Just keep the amount of water in your drain pans, like under 1/2 inch (max).
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Then once a week, remove, wash & rinse each of your drain pans (aka-overflow reservoirs). To avoid a build up on nutes in the coco, just feed, water, water, feed, in rotation.
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Any nutes can be used with coco, if they have higher P & K numbers. Since coco tends to lock up P & K, withholding it from your plants roots until enough is present.
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I'd just start off with 1/2 oz of GIG (NPK 5-2-5), and a light dose of FP (NPK 1-8-7), like 1/4 oz per gallon of water. That would give you a NPK value of 5.5 - 6 - 8.5. Then the very next feeding, use only 1/2 oz of FP (NPK 1-8-7) per gallon of water.
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The key to this strategy is simple. A good amount of the P & K just get locked up in coco, there is no avoiding it. So you have to give more P & K thru the whole grow. By alternating fertilizer mixes, you let the N get used pretty much as you go & keep just enough extra P & K to ensure the roots actually get what they need. Since, that coco is going to be holding onto & not letting go of a fair amount of P & K.
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Depending on the strain you are growing, you may need to feed more (slightly stronger mixing strength), but probably not less.
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The feed, water, water, feed, in rotation - is basically a ongoing light flush that helps avoid build up of nutes in the medium (coco), so Mary stays happy & healthy......
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GHOPZZ.... Yes, start dropping the mixing strength on the GIG and start using the FP. This will help when you switch the light schedule. The plant will read both the reduced light / greater darkness and reduced N as signs / triggers to start flowering.
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For a bloom boost, I'd just mix the FP at 2 oz to a gallon of water and give each plant only one quart. That makes a nice "one time" boost, that will not fry your plants.
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I'm not much of a fan of the 0-50-30 bloom boosters, made by just about eveyone who sells ferts. They kill the micro-beasties in your soil and can easily toxify your soil and cause huge pH swings (that equals - nute lockout). I've seen these over-used and yields actually went down.....
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When it comes to yields, either the plant is a good yielder or not, it's mostly genetic.
I also forgot to add, that on straight coco grows, you do have to adjust the pH (of your water and/or nutes) into the range of 5.2 to 6 for best results. Below or above that, and you will have nute lockout issues.
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Somebody041.... Organic nutes will register on pH meters. When you mix them up, they will change over time (either going up or down - a lot depends on the water you mix them with).
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You've probably heard that TDS meters don't help much with Organic Nutes, that is true. You can't read Organic Nutes with a TDS Meter like with chem nutes to determine feeding strengths.
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With organics, you have to follow the label on bottled stuff. Or if making your own, follow receipes already worked out by others through trial & error.
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For coco growing, you need your nutes in the 5 to 6 range of pH for best results. Shoot for the middle of that range and it's all cake.
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It helps a lot to read the pH of the runoff twice a week. Just take some water with a pH of 6 and pour it through until you get runoff. Take that runoff water and check the pH. Did the number go up or down from the pH of 6 your poured through ?
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If it went down, you can make a mild High P Bat Guano Tea and add it, instead of a pH up product.
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If it went up, you can make a mild High N Bat Guano Tea and add it, instead of a pH down product.
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You can use pH up & down products (in moderation) in organics, but I prefer to use amendments like guanos to balance things out. Use of pH up or down products from a bottle, as a general rule, equals the death of some micro-beasties (not all).