I have the DP-4, but only for about 3 months. Like @PortalMasteryRy
, my doses are 10ml, mainly because I found that slight variations in daily dosing with a DIY I had created, were greatly mitigated at the 10ml level. Although I calibrated the DP-4 pumps, they did drift slightly, over time, which could also be a function of the differences in flow rates depending upon the amount and type of fertilizer going through each pump. So, again like @PortalMasteryRy
, I calibrated timing based upon measurements of actual doses.
In about 5 years of various auto-dosing schemes, with DIY mixes, I never encountered any precipitation issues with micros or NPK. So, no mixing was/is required over the 30 days of dosing. However, various salts involving Mg and Ca did result in some troublesome precipitation even though I was well below solubility limits. So, I set lower loadings that did not cause such problems, but these would them need more than 10ml doses.
I should point out that my reservoir setups, including the current DP-4, are all fed from the bottom of this 300ml canister (30 days at 10ml/day): https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
. This is a hanging reservoir and easily refilled without disturbing the setup.