Trying to do the math on an affordable HPA system

If you expand the 50 micron example to include the full 5-80 micron range, filling space isnt a problem. A single 50um droplet has the same volume as a thousand 5um droplets. To get a handle on the size difference, if the 5um droplet was a grain of granulated suger, the 50um droplet would be a snooker ball Note the volume of the grain of sugar is equivalent to one thousand 50 um droplets in the real world so they are not that easy to see
You`ll find it easier if you work on the premise that the basic principle of aero is closer to soil than hydro. The aero root structure has more in common with soil roots than with hydro roots. Aero could be described as the perfect soil minus the actual soil.

If 1.0-1.6EC is 1/4-1/2 of your normal feed then yeah it uses less.

OVERALL it uses much less fertilizer.

You use a lot less water, and therefore use less fertilizer when compared to other methods.

I feed 6g/gal of megacrop from seed/clone to harvest because I feed the veg/flower area from the same res and run perpetual.

Atomizer said:

If you expand the 50 micron example to include the full 5-80 micron range, filling space isnt a problem. A single 50um droplet has the same volume as a thousand 5um droplets. To get a handle on the size difference, if the 5um droplet was a grain of granulated suger, the 50um droplet would be a snooker ball Note the volume of the grain of sugar is equivalent to one thousand 50 um droplets in the real world so they are not that easy to see
You`ll find it easier if you work on the premise that the basic principle of aero is closer to soil than hydro. The aero root structure has more in common with soil roots than with hydro roots. Aero could be described as the perfect soil minus the actual soil.

Click to expand...

Im with you on all of that, except for the snooker ball comparison. Im either way off on what a um is or you added or dropped a decimal place in there somewhere. Isnt the difference between 5um and 50um a factor of ten on the diameter? Snooker balls are a little more than 10 times the diameter of the grains of sugar in my cereal

dstroy said:

If 1.0-1.6EC is 1/4-1/2 of your normal feed then yeah it uses less.

OVERALL it uses much less fertilizer.

You use a lot less water, and therefore use less fertilizer when compared to other methods.

I feed 6g/gal of megacrop from seed/clone to harvest because I feed the veg/flower area from the same res and run perpetual.

Click to expand...

Im a Mega Crop guy too. I eventually settled on an EC of 1.3 in my last grow. That seemed to be the level the plants wanted based on EC changes in the rez between water changes. That was in a re-circulating system.

Now you two have me confused again - not an unusual state for me - because you seem to be recommending very different EC levels..

Your 1.0 - 1.6 EC recommendation is what I considered 'normal', or at least a commonly recommended EC range in hydro. Plus its in-line with what worked for me last time.

Now that I look back on Atomizers earlier posts, Im not clear what exact EC level he was referencing with the 1/4 to 1/2 comment. I took it to mean that what ever level you ran with other hydro methods, you should cut back to 1/4 to 1/2 of your previous EC levels when doing HP aero.

Im not tooooo worried about setting EC levels. Mega Crop seems to be very forgiving when it comes to over or under feeding, or at least more so than my previous liquid nutes. Im planning to start by rooting some fresh clones, so I will be working my way up from plain water, or very very low EC levels in the beginning.

Hopefully Atomizer will chime in and clarify his comments.

Hi Atom, Larry,

If I have 6 misters (1GPH) in a 26 gallon tote, do I just multiply the 50 sec interval by 6? so spray 1.5sec every 3 min for later growth?

“In an ideal system, you would set the misting duration based on flowrate and chamber volume. For early growth, the misting duration would provide 0.02ml -0.04ml per gallon of chamber volume. For later growth, 0.06ml per gallon.
The interval between mistings is adjusted to provide the target daily throughput, which will be somewhat dependant on environment variables (light,heat etc). As an example, a 26 gallon chamber with one 1gph nozzle would need a 0.5- 1 second misting duration in early growth and upto 1.5 seconds for later growth. The interval between mistings for early growth would be 35-70 seconds (dependant on the misting duration setting) with a target daily throughput of 1.3 litres. For later growth, the interval would be around 50 seconds with a target daily throughput of 2.65L. The name of the game is to inject mist little and often to maintain an optimal aeroponic environment.”

Dont listen to what Im about to say Im still trying to figure this stuff out, but Im going to treat this like a spot quiz and see how close I can get.

Wait till one or both of the real experts (drips under pressure??) chimes in.

That comment came from Atomizer, so I will give you my take on it, and hopefully he will correct me where I get it wrong. Then maybe dstroy can chime in with his thoughts as well. About the only thing Im sure of with growing this weed is that its a lot like playing hand grenades. As long as you get close, the plants will do at least ok. Plus, there are almost as many "best ways" to grow this plant as there are growers!

You dont multiply by the number of nozzles. You use the minimum number of nozzles you need to get good coverage over the entire chamber. Then adjust the ON time to fill that chamber with mist - but not too much mist.

My take on it is that you want to start by adjusting your mist ON timing so that the chamber completely fills with mist - not too much and not too little. You want to be like Goldilocks and get it just right. Im not completely sure exactly how to judge that yet, but thats the goal.

Once you get the ON time adjusted so the chamber completely fills on each ON cycle, and you have good coverage, you dont mess with it again. In order to adjust for the plants wanting more food later in the grow cycle, you reduce the OFF time, while leaving the ON time alone.

Increasing the ON time just gets things too wet, and you wont get those fuzzy aero roots.

Larry3215 said:

Im with you on all of that, except for the snooker ball comparison. Im either way off on what a um is or you added or dropped a decimal place in there somewhere. Isnt the difference between 5um and 50um a factor of ten on the diameter? Snooker balls are a little more than 10 times the diameter of the grains of sugar in my cereal

Click to expand...

You are right, getting a decimal in the wrong place is what comes of trying to do math at 5am It should be 5mm, the snooker ball would be equal to 500 microns..which happens to be the average size of a grain of sugar so that may be where the calculation jumped track
With nute strength you start low to be safe. You run DTW and track the run off ppm which allows you to make the necessary adjustments. If you are delivering too much mist, the information will be hidden by the volume of run off. Plants will tolerate a higher EC when you are overmisting, you`ll discover they`re not as forgiving of EC when you are in the right mist ballpark. I monitor inlet and outlet ppm`s with dual probe tds meters. The probes are plumbed into the lines so i can compare the difference between the in/out ppm at any time. A HM Digital DM 1 is the cheapest option but if you can stretch to the DM-2 you`ll get much better build quality and shielded probe cables, the only issue is the green in/out indicator led`s are way too bright.

I love my BlueLab truncheon meter, but its not all that precise. It only has a resolution of 50 PPM on the 500 scale, and the lowest reading is 100 PPM, so Im not sure how well that will work for this application. Im going to try it first and see how well it works. One of its nice features is it can read in very shallow water, so it would be easy to check any nutes that collect in the bottom of the chamber, or drip into a small collection container.

Im assuming you rig something up in the drain or bottom of your chamber to place the OUT probe into with the DM-2?

The bottom center of my fabric pot hangs down forming a nice bowl. I was thinking of putting large stainless nut there to form a collection point for any runoff with a small container to collect it for measurements. Anything that over flows will go into a water heater drain pan I have below the pot.

The HM DM-1 is on my future parts list, but I'll change it to the DM-2. Amazon has the DM-1 for like $21. The DM-2 is on sale for $38, so it would be well worth the extra for the DM-2 I think. I can always put tape or finger nail polish over the LED's to tone them down.

Sounds like I got at least a B on that spot quiz I may have to revise my hand grenade analogy as far as HP aero watering goes though....

I think this is going to be fun - even if I kill the next 10 clones I start

Well crap. The new tank arrived today, but it's damaged. It has significant dents. At least Amazon makes returns relatively easy.

I just finished roughing in a control center, and as I was taking some pics, I realized I forgot to make room for the STC-1000's. Fortunately, I have plenty of time to re-do it - now that the tank is going back. Im not really upset about re-doing it - I already thought of a couple of improvements to the layout that will make routing the tubing better.

Here is a pic anyway as promised.

I use a bluelab for measuring nute strength but its no good for comparing in/out ppm. The DM meters read 0-9999ppm and because they have 2 probes you dont have to worry about one being different to the other. You dont need the accuracy of the bluelab for comparing one reading to another. I fit probes into the drainline via a15mm JG speedfit tee which are ideal as you can empty/reset the sampling reservoir by rotating the tee 180 degees. The small reservoir is needed because there isnt enough run off to fill the pipe. it drains into the downward facing center outlet and once full the excess overflows so it provides a constant reading. If you get the hypro nozzles they will come with gloss black flexible protective caps made from something similar to plasti-dip. These work great as flexible stop ends for 15mm pex tube. Punch a hole in the cap with a drip line hole punch. Cut a 45-50mm length of pex pipe and with the help of some hot water stretch the cap over the tube and push the "out" probe into the cap. It`ll be 100% watertight.
Catchment trays for the run off can be made very cheaply, make a simple frame from timber that is larger than the base of the chamber. The size of the timber depends on the size of the chamber but generally you wont need more than 3"x 1". On the bottom of the frame you need to fit a cross piece to attacht a 15mm JG tank connector. It can be anything like aluminium strip or channel but it must be at least 2" wide and not very thick cos the tank connector isnt designed for thick walls. You can use thicker timber or plywood if have a forstner bit to create a recessed hole for the tank connector. Once the frame is done, take a piece of 6mil poly and staple it to the top of the frame ensuring its fairly taut. Melt a hole in the center slightly smaller than the tank connector so its a good fit. Push the tank connector down into the hole in the cross piece, tighten it down from underneath. Fit an elbow to the bottom of the tank connector and you should have a nice cone bottomed catchment tray for the run off.
I always cut the bottom of the tank connector down to a couple of mm so its more flush, you can do it on a belt sander too, the idea is to remove the 6 vanes and wall on the bottom of the fitting so its completely smooth.
Here`s one of my more radical catchment tray solutions, a 2" pond bottom drain traps the poly and carries the run off away. The permatron chamber floor is attached under the cap of the tank connector on top of the white plastic disc (chopping board), the standoff tubes provide the gap so the chamber floor and catchment tray are both cone bottomed.


That blue songle relay on the timer should be removed and thrown into the nearest bin

Those are some excellent ideas! Im going to steel some of them for sure.

It just occurred to me that I may not get nearly as much runoff as you do. Your using trampoline fabric. If thats anything like whats on my old exercise trampoline, its pretty much water proof as far as absorbing water. The fabric pots I have will act more like a sponge, and may tend to hold the over spray until it evaporates rather than letting it collect in the bottom of the chamber. I'll have to see how that goes when Im testing the nozzles.

Yeah, the relays are history as soon as I get the mosfet switches wired up. I have all the components, but I need to look up the pinout on the relays so I can figure out the connections to the timer board once they get de-soldered. Im pretty sure Im going to need to add a jumper or two once they come off, and maybe a resistor where the coil was connected. I'll have to look into that.

I bought two timers so I can set up day/night schedules once I finish messing with seeds/clones, and start a full grow. I think Im just going to buy an SPDT solid state relay from digikey and use it to switch the power back and forth between the two timers when the lights turn on/off. I'll just use a cheap wall wart supply from my parts box to trigger the relay when the lights come on. The low power (5 watt) SSR's are actually cheaper than buying the components separately.

The easiest way is to desolder the relay and then solder jumpers from the old coil pads on the pcb to the connector terminal pads. That will effectively shunt the coil terminals to the now useless connector block. Note, the colour coding of the blue and brown jumpers in the timer vid are not correct, i couldnt be arsed to desolder them lol. Knowing the polarity is important because the coil voltage is the same as the timer (12v) and there is a flyback/freewheeling diode fitted on the pcb. If in doubt reach for the multimeter

Thanks! I was just about to go searching for that video again. I didnt pay much attention the first time because I was planning to use different timers.

Thanks again. I was just about to go looking for that video. I didnt pay much attention the first time because I was planning to use different timers. I see what you mean about the short jumpers to the coil pads. I (almost) always double check things with a DVM anyway

Here’s what I’ve been working on



a doser

Thats just - wow. I can do stuff like that too - in my dreams!

Awesome stuff!

Well crap. My bad luck streak is continuing. The replacement accumulator tank arrived today and it is also dented all to heck, so its going back too. Now to see if I can find a different brand that maybe knows how to package these things.......

The second and third bad things that happened are more likely due to user error, but I managed to kill both timers trying to remove the relays!

I dont know what I did wrong. The first one was a "simple" de-solder job, but once the relay was removed and the jumpers added, the board never would power up again. I dont know what happened unless I over heated something else on the board, so I cut the relay case open on the second one, removed the coil connections, and contact points, then soldered leads to the posts inside the relay. No heat was applied to the board at all. This time it powered up, and seemed to be counting down, but there was no trigger voltage on the posts. Well, actually the problem was the trigger voltage never went to zero. It just stays at 12 volts no matter what.

The good news is the mosfet switch I built based on dstroy's diagram works perfectly - I just dont have a timer that will trigger it.

I found a different timer on Amazon that is solid state, and cheap, so I ordered one of them to try out. It only goes down to .1 seconds intervals, but that should be good enough. The user guide sucks, but the instructions look vaguely similar to the FRM01 timers, so maybe it wont be too hard to figure out how to program it.

https://www.amazon.com/gp/product/B01J5JSE0Y/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

The other good news is the Hypro nozzles came today, so I can do some playing around at least while I wait for more parts....

Atomizer said:

I use hypro`s and netafims and neither drip, the adv`s open at around 4 bar ~ 58psi. Throw the tefens into ye olde aero spares box

Click to expand...

My new Hypro's drip! Maybe even more than the tefens. The seem to open, or at least start dripping, around 30-35 PSI. They dont make good spray until around 50 PSI or so. I didnt get a good number on when they close.

Any idea why?

I made a short video running them at 80 PSI. I will post the link as soon as it finishes processing.

Here is the video.

The vid wont play for me but if the nozzles drip at 30-35psi i guess they`re not the anti drip version cos they wont do anything below about 58psi. The pressure at the nozzle may not be the same as the pressure gauges on the control board. I always measure water (and air) pressure right at the nozzles. I run 15mm pex tube on all my tanks to keep potential pressure drop to a minimum and ensure there`s no shortage of flow to the solenoids. JG 1/4" ldpe tubing has a bore of 4.3mm so its best used for very short runs after solenoids or for teeing pressure guages, pressure switches, relief valves etc off the main line.