First month of hydro growing and I brought a sunflower seeding almost to two feet tall. Also have tomatoes and cilantro growing in other DWC buckets with a l lot of trial and error. I've found water/nutrient changes to be the most time-consuming and complex part of this operation so far and am looking for ways to simplify. I've started adjusting nutrient mixtures with a lot of trial and error to see which plants like what. Have been using RO water and adding a bit of CalMag because I understand tomatoes need more than other plants. Also, I feel like the tables on the side of the bottle might be heavily biased to growing one specific type of plant, which is fine but figuring out what things like these plants would like best isn't as clear lol.
Several times now I've mixed up solution to find the PPM reading to be over 1,500, once in the 2,000 range. My sunflower quickly showed that it did not like that much nutrient and I diluted it the next day. I think something similar happened in another bucket but now I'm reading that tomatoes like EC in the 2,000 - 3,000 range. I've been frustrated adding a certain number of tsp/gal only to find the EC at the end much higher than I expected it would be. This is also problematic when trying to figure out what to add for makeup water (so far I have only air stones and each 5 gal bucket is separate from the others).
To this end, I decided to do an experiment and measure the PPM when 1/4 tsp of nutrient was added to 2 cups of 0 PPM water. I calculated the ratios to determine how much of each nutrient mix needs to be added in order to obtain a certain PPM amount. My thinking is that this will give me the ability to easily mix by adding a certain amount of nutrient, check the PPM reading and if it is in the expected range, move on to the next nutrient. I'm using the GA Flora 3-component and found that each of the three components is quite a bit different with the N-heavy Micro component on the high-PPM side and the K-heavy Bloom component on the low-PPM side, alongside the CaMg solution. In addition to being easier to not accidently overshoot and end up with mix PPM 2x or 3x higher than desired, I find this is also useful to have a better idea of what percent of the nutrients is N/P/K/CaMg.
Any thoughts on this system?
I haven't broken out elements for the different 3-part components. While getting started I've just considered Micro N, Grow K and Bloom P. Below are the multiplers and how I've been using them.
N (Micro): 0.00527
K (Grow): 0.01363
P (Bloom): 0.02321
CaMg: 0.02596
The multipliers can be used to determine either of the following:
1. How many mL of nutrient to add to a given number of gallons of water to increase by a desired PPM.
2. What PPM increase to expect after a given number of mL are added to a given number of gallons of mix.
I am not sure if there are any issues with linearity or if these equations are accurate when other nutrients have already been added to the water but I have tested the CaMg calculations and they seem to be accurate (I can't say how accurate because the water levels were approximated).
For #1:
# mL Nutrient to Add = multiplier X gallons mix X desired PPM
For instance, if 600 PPM of N (Micro) is desired in 5 gallons of mix, then the equation is:
0.00527 * 600 * 5 = 18.51 mL of N/Micro nutrient
For #2
Expected PPM = (# mL nutrient added / gallons of mix) * (1 / multiplier)
For instance:
If 15.81 mL of N (Micro) was added to 5 gallons of mix the equation is:
(15.81 / 5) * (1/0.00527) =
(15.81 / 5) * (189.75) = 599.99 PPM
I'll be trying this out for the next few weeks to see how well it works. My plan is to calculate mL values and add to mix, check PPM readings to verify they are where they are expected and then continue with the next nutrient. Then, if I need to mix up extra mix, it'll be a matter of matching those exact sample PPM readings after each nutrient is added.
My long-term goal is to get away from using measuring cups/spoon/droppers at all and slowly pour nutrient mix straight into a larger reservoir with a bubbler/strong pump in it, mixing the solution quickly. Then I can just watch the PPM reading and stop pouring when it gets to the correct number. Let the mix continue to circulate for a bit, add the next nutrient and move on. At that point I'm probably going to be asking the question of how long a PPM meter can be left in water or if there is one designed specifically to be left in the water 24/7. Then, maybe just automate the dispensing of nutrients but that's a long ways away seeing that I'm still working on my first couple of plants.
After further work with this I found that the PPM increases for the Micro formula were not at all consistent. I think this may be in-part because I had not shaken the bottle up well enough. I haven't been shaking the bottles very well because every single time I end up with solution spraying out the top. Every bottle, regardless of how hard I tighten it. I've been thinking about adding some teflon tape and long-term need to find another container to keep the solution in because these bottles are junk.
That said, I'll plan to come back here with additional data if I get a chance to collect it in the future.
That said, I'll plan to come back here with additional data if I get a chance to collect it in the future.