My reservoir STINKS

Mr PSI -- You didn't comment on using PK additives during flower. Whats your opinion? and what additives & nutes are you using?

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Well, I wouldn't even call bloom boosters additives per se. They should more appropriately be called supplements as they just boost Phosphorus and Potash which are found in everyday fertilizers anyway.

Bloom boosters are ok, but should be used sparingly and only in the later stages of flowering. Alot of them are extremely potent, eg. Grotek Monster Bloom has an NPK value of 0-50-30 which can easily burn your plants if you're not carefull. I don't use them myself because I don't really see them as necessary.

I use GH Flora series. It's a 3 part nutrient formula, which has a good reputation in the hydroponic community. The reason why 3 part nutrients are preferred in hydroponic growing is because the solution can be tailored to the plants specific need at a particular phase of growth.

Example:

The GH Flora series contains a "Grow" formula, a "Bloom" formula, and a "Micro" formula.

Here's how they break down in NPK values (ignoring micro nutrients):

Grow 2-1-6
Bloom 0-5-4
Micro 5-0-1

Example of usage in typical plant growth phases:

Veg Phase
-----------
1 unit of Bloom + 2 units of Micro + 3 units of Grow (or)
1 x (0-5-4) + 2 x (5-0-1) + 3 x (2-1-6) =
0-5-4 + 10-0-2 + 6-3-18 = 16-8-24 NPK

Transition Phase
----------------
1 unit of Bloom + 1 unit of Micro + 1 unit of grow (or)
0-5-4 + 5-0-1 + 2-1-6 = 7-6-11 NPK

Flowering Phase
---------------
3 units of Bloom + 1 unit of Micro + 2 units of grow (or)
3 x (0-5-4) + 1 x (5-0-1) + 2 x (2-1-6) =
0-15-12 + 5-0-1 + 4-2-12 = 9-17-25 NPK

You can do this with any 3 part or 2 part nutrient formulation and get basically the same result. I just wanted to show you an example of how a simple 2 or 3 part nutrient can be used in varying amounts for any phase of plant growth.

So, you really don't need a bloom booster when using these kinds of nutrient formulations as you're providing all the potassium and phosphorus that the plant needs in the flowering phase of growth.

Does that answer your questions regarding P&K?

As a followup, here's a post by Uncle Ben on the abuse of Phosphorus during flowering:

The never ending abuse of Phosphorous to enhance flowering

Contributed by: Uncle Ben

A common mistake for growers when they reach the flowering stage is to start hitting the plants with a high P fert like 10-60-10, continuing to use this blend exclusively, and when their plants start experiencing a deficit of N or micros as reflected by the dropping of lower leaves and chlorosis, they wonder why. Plants flower as a response to long nights, not because of fert blends high in P. A ratio of 10-60-10 is WAY to high in P. The plant will only take what it needs and compete for other elements that may be more important at the time.

You may have heard that too much N can inhibit flowering. No question about it, exclusive use of a plant food that is rich in N such as blood meal, a 5-1-1 blend, or ammonium nitrate may inhibit flowering especially if the phosphorous level is low, but most balanced blends have sufficient amount of P to do the job. Manufacturers/horticulturists will give you element analysis and what effect the elements have on plant growth, but remember this does not necessarily mean you will get better yields. Using a high P fert exclusively during flowering can actually work against you. It's an abundant amount of healthy leaves going into 12/12 that produce a lot of bud, not high P ferts.

I rotate fert blends as the plant *requires* them, not because it is "the thing to do." For example, when your plants are going thru the stretch phase during early flowering, they may need more N, especially if you're getting some yellowing in the lower/mid leaves. Give up the cannabis paradigms, and give them what they need. Go back to mild high P fert when the stretch ends, maintaining the foliage in a healthy state of growth until harvest for maximum yields. A 1-3-2 blend such as Peter's Pro Blossom Booster, 10-30-20, is one of the best flowering blends on the market because of several factors - it is higher in nitrate N and Mg. It is sold under the Jack's Classic label. An added benefit of Peter's blends is their use of high quality, very pure salts that will cut down on root burn.

Mr. PSI -

Thank you once again for the learning lesson on hydroponics. I can see there's a big difference in how organic and chem nutes work.

I'm going to stick with the chem fert for awhile. They've made my grow a lot easier with less PH fluctuation, more accurate PPM readings, ect.

Thank for PK info. Thats what I was looking for. I didn't think all the additives were a waste of time.... Ill add some PK boost and look for the results.

I'll report back soon with my results & pictures

Glad I could help you out.

Any recommendations on a good PK booster to use during flowering?

Again, If you haven't already bought some, I wouldn't bother. But, to answer your question, the only ones I have any experience with are Monster Bloom by Grotek, and Kool Bloom by GH. They are equally as good IMO. Just make sure you go easy on the stuff and only use it after the stretch phase (about 4 weeks into flowering).