iGrow

3 hours ago, greenkush said:

You could introduce a second pump to drop wise with a base chemical and that way you cover both directions, but I don't really see the need for it, other than for fun.

Agreed

8 minutes ago, greenkush said:

I never really worried or factored in time-to-count logic. I do constant readings of the levels and treat it as a drop wise solution, drop; mix; wait; mix; measure; drop, rinse and repeat. Due to the rate of the drops I don't really need to worry about excessive overshoot. But with all that said, it was really just done as a hobby project one afternoon for fun, so I was not really concerned about 0.5% accuracy.

Edit as per your edit: The impeller was used as an agitating device to mix the solution around to ensure the acid gets fully saturated. It does not do anything to the pH

Edit 2: I think you're over analyzing the solution and desired outcome. It's really not as complicated as you think.

I think I’m over analyzing. It’s a slow changing system, so it is as simple as drop-mix-measure. This only addresses pH in one direction? So glad I saw your approach, was about to start this process from scratch! 

17 minutes ago, greenkush said:

I've designed an automated PH up/down mixing solution. PH probe that runs to a controller, controller controls a impellar to mix solution, another signal controls a peristaltic pump and then its just a matter of doing some base line determination in order to figure out what the total  PH increase will be based on the release of the pump, once you've done that you write an formula to determine the run cycle of the pump in order to achieve the PH level. Obviously some caveats would be impurities of your water at that point in time. In reality for small scale use its kinda impractical, but when you're dealing with huge grow ops it would be far more beneficial.

Ahhh. I did a lot PDI controller coding at varsity... will need to do some serious catch up and refreshers in PLC to get your type of setup going.

Controlling the pump to address pH... there must be some serious dead time/lack of proportionality issues with that... or did you get around that by pre-mixing an acidic buffer and pumping as the pH goes up? I’m a bit confused how the impeller needs to be controlled to affect pH? Sounds like a really fun DIY project! 

Advanced stuff. Really interested in how that turns out and any testing you do. I wanted to setup my Raspberry onto something like that eventually, doing pH now. Still figuring it out. 

1 hour ago, greenkush said:

Cool, yeah i'm busy designing my own lightning system, hence my reason I got one. I also built my own color spectrometer that allows me to check the wavelengths. It seems relatively accurate if I compare it to a friends 25k one. 

Nice one with the spectro. I want to go that route too! PARs don’t tell the whole story without knowing those wavelength breakdowns. I’m gonna work on that this week. 

@Trailblazer420 I do sometimes wonder if it makes more sense to get a luxmeter and use a conversion factor to estimate pars, based on the cost of the quantum’s.  

I spent 6-7k on the sensor, with friends. I have other uses for it, checking ‘cold’ spots in my other grows. 

I do DIY and have multiple SMD and COB setups that I test.  Like I said, everyone just wants to sell their gear without the test results. I MUST know, there are too many variables... Haha

I’d love to hire/lend it out. Just nervous about guys damaging/not returning it etc. If anyone has suggestions, I’ve tested the hell out of my grow area already. 

I find with lighting everyone has a theory and nobody does the testing. 

I’m really curious as to how LED burn works,  I’m hanging my lights at 15cm which seems way closer than advised, but the temperature is fine and my readings say 800 directly under them... so it should be fine/ideal? 

@greenkush I tested using an Apogee SQ520 quantum meter. Was expensive but I got tired of guessing. 

I’ve been using multiple 65W HLG grow lights and getting 800PPFD when hung 15cm from the canopy with no burn. How close were your lights to get that and do you know the resultant PPFD?