LED HPA Grow Room 🌱 💧 🔨

Last year I did some upgrades to the grow room and changed from my ebb and flow siphon setup over to high pressure aero. I love playing with new and different setups, so I’m always tweaking things. The system is currently a few weeks into flower for its first run, but I thought I would go ahead and document what has all happened (and changed) since I initially built things out.

The plan is for 3 grow beds with one plant in each, running HPA via a shared system under 4 HLG-300’s.


The initial layout as planned looked something like this, using mostly John Guest fittings and quick-connects to keep things simple and leak-free.

I had been looking to decrease the size of my reservoir this time around, so I could maintain less water (and hopefully use a lot less as well). I settled on a pet food container from Chewy.com.


Food-safe, lid that sealed nicely, and with a little insulation wrap it would be good and light-proof. We built a small stand for it, since I didn’t want the cement causing issues with water temps.

I had been using laundry sinks for grow beds for a while now in the previous ebb and flow setup, so I continued with that so I could quickly connect drains and I knew there would be no water pooling in the bottom. (Like the res I would be able to prevent light leaks by wrapping these in insulation.)

Notice the strange drain in the middle of the room? That was there when I moved in, so we re-routed it and would use this as the drain-to-waste outlet.

We then painted the drywall white and insulated the other two walls, leaving one run open so we could pull air from up high in the garage and lead it into the room at the bottom.

I wanted to see what the QB’s were going to do in this space, so we ran some slotted L-channel on the ceiling and hung the lights for a quick test. (These suckers are BRIGHT!)

We installed the exhaust fan, AutoPilot controller, and ran the initial connections for a first test of the HPA.

The “lids” for the sinks were created by cutting some plywood into the proper shape the coating the bottom with Pond Shield. I didn’t want anything toxic like spray paint or Flex Seal, so this was perfect.

The tops were covered with panda film, the HPA lines were connected, and the sinks/res were wrapped.

At this point the room was pretty well setup and ready to go. Feel free to ask any questions you might have to this point, tomorrow I’ll go into problems that came up and the changes that were made to combat them.

Until then, I’m off to dab myself to sleep…


Awesome build man and great thread can’t wait to see it in action


Ready for the show :popcorn:


Holly cow, you don’t have twos left hands, man ! ^^ Aero become rare, funny to see than it don’t die in some mad minds lol


Amazing to watch you put your setup together.

Hoping to learn a few new tips and tricks. Thanks for labeling the parts in the first pic, really helps.


When I first starting gather parts for the build I ran across a company called Multiponics. It seemed like a good idea at the time, since I could place a single order and get most of what I wanted. It cost a little more than buying it all myself, but the ease of ordering (and helping a small business) sold me.

Unfortunately it wasn’t until after I had placed the order that I went and read the reviews on the company @ Facebook. Apparently delivery times were anywhere from 3-9 months. I started to complain to the company after 2 months – and it ended up taking me another 2 months to get my order (a year later and I still don’t have everything I ordered).

So in the end I really didn’t save any money or time. To ensure no-one else follows this road I went ahead and put together a parts list from Amazon for most everything. Each of these has alternatives that might save you some cash (some non-prime) – but I opted for Prime items when available.

150 Micron Pre-Pump Filter

80-100psi Pressure Switch

John Guest 3/8 One Way Check Valve

Aquatec 8800 Booster Pump

3 Gallon Pressure Tank (I went with 2 Gallon, but you can size as you wish.)

25-200psi Adjustable Pressure Relief Valve (Super important, otherwise you just created a bomb.)

12v Normally-Closed Solenoid

Mean Well LED Driver (Drives Solenoids w/ Zero Lag)

8-Way Terminal Block (For Splitting Driver Current to Solenoids)

Tefen Misting Nozzles (Many Alternatives Available)

In-Line TDS Meter (Thought this was a good idea, it’s useless w/ no flow.)

Now that we got that out of the way, onto the next phase… The first tests of the system and dropping in the first clones.


Nice clean write up so far. Excited to see how this works out for you. :book: :eyeglasses:


In the parts list above you’ll notice I went with a Meanwell LED driver to power the 12v solenoids. Prior to that I was using a cheap little transformer that was found in my “random box of shit”.

That transformer had a slight delay when fired up (anywhere from 0.5s to 1.5s). This caused a bit of drip, as the solenoids opened slightly for a fraction of a second before they fully opened. (Trying to save a few bucks cost me a week of delays.)

Converting to the Meanwell driver also means I can expand the # of solenoids in the system. In the future I might migrate the solenoids and nozzles to the edge of the tub (not the lid), and run a solenoid per nozzle. Right now I’m not sure the benefits outweigh the added cost, though.

The good news is that with 4 nozzles per bed I am getting a super strong mist with full coverage. Using the Meanwell also meant I could dial the AutoPilot all the way down to 1 second ON times to prevent droplet formation on roots.


Outstanding write up!

What kind of on/off times were you running before and what are your target times this time around?

I cant remember if you mentioned it, but are the nozzles you’re using no drip or regular? Using no drip might help with delay starting and run-on dripping.

I will have lots more questions once I finish looking closely at your pics :slight_smile:


I played with everything, both ON and OFF times. As low as 1s ON and as high as 3s ON. (Far too much, haha.) For off times I tested between 1m and 5m – never got too much further than that since they were drying out pretty well at 5m.

Right now I’m running 1s ON and 3m OFF, which seemed to be a good middle ground for how things are setup now.

I’ll be posting the initial planting and first set of problems today, just have a few annoying calls to get out of the way first. Unfortunately I got hit with $100k overage charge from my web hosting provider so I’ll be a bit busy until around 5pm.

After that it’s going to be Rzr time on the trails to de-stress a bit. :slight_smile:


Holy over charge batman!! Good luck!


Sweet set up man can’t wait to so the show!:popcorn::seat:


Is this seat taken? :seat:

Damn I missed the intro but it sure as hell looks good. Teach us your ways!

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Been a busy week and I got a bit side-tracked, but I figure I better get some more details on the first test run before I head out for vacation tomorrow night.

Quick Recap
High Pressure Aero running Drain-to-Waste
HLG QB-300 (x4)
Ionic Nutrients

March 28th
I had initially set two clones aside in the aerocloner to move directly into the HPA system. Unfortunately one of my partners got a bit impatient to start a new batch and went ahead and planted my two clones in dirt to free up the cloner.

I believe this was a good start to some of my issues w/ dialing in the system.

I cleaned the roots as much as possible, knowing I was going to stress the hell out of these plants by doing this. Even then I was still not able to free all of the dirt as they had become rather bound up in the cups. Once I cleaned as best as possible I dropped them into the grow beds.

Bear Klaw (Right-Side Bed)
Unknown genetics, locally bred, annoying to grow but a favorite around here.

OC (Left-Side Bed)
One of my favorite sativas that has a very healthy mother.

I started with my timer setup to run 1s ON and 5m OFF, but they were showing signs of underwatering rather quickly. They were wilted and the leaves were getting crispy with very few new roots showing. I turned the timer down to 1m OFF before I finally saw them start to recover with nice new white roots hitting the bottom of the bed by the 3rd day.

At this point the problems started showing up and compounding. Unfortunately due to the number of issues I don’t have 100% clear logs, but I can discuss each issue and how we attempted to work around it (and those that are still left open). I will post each problem on its own below as I piece together what all happened.

Here are how the plants looked last week during the 2nd week of flower. A lot better than what they looked like when they started, but still not as good as I normally get. The BK is still a mess, but at least the OC will produce.


They look pretty happy in those pics!

Looking forward to more details :slight_smile:


I’m back from vacation. The drive from Denver to New Mexico was beautiful and we got to spend some quality time totally disconnected from the world. This is the first real vacation I’ve taken since I launched my company over 5 years ago – it’s amazing how quickly time can fly when you’re building a business.

The girls received a good dose of LITFA the past week since my tender only stopped by twice to refill the res. Once with a pre-mixed batch of water and the second time with straight water from the hose. (Not even lake water like I had been using.)

I was exhausted last night after 2 days of travel so I only stopped in the room for a few minutes to make sure things were ok before I crashed out. The girls are looking good and I will post some updated pics later today after lights-on. Not as much growth as I had expected, but I will know more once I check the pH and EC of the res. My guess is they are feeding on themselves at this point. I’ll be mixing 10 gallons of nutes up today and topping the res, plus doing some trimming as there’s some yellow leaves scattered around. I also noticed the two plants have started to grow into each other so I will need to tie up some branches to get an equal amount of light on the canopy.


I finally went out to the room last night and I discovered I had made a mistake.

When I flush my res I switch my timer from 1m OFF to 3m OFF to conserve solution in the accumulator and prevent the system from pumping from a dry res or taking up my flushing agent. Unfortunately it seems I forgot to switch the timer back to 1m OFF while I was on vacation.

I was out looking at the plants and what I thought was “a little yellowing” was actually quite a bit. And all of the branches on the OC that were extremely strong when I left were now leaning from the weight of the buds. I tied a few things up for now to keep them off each other and ordered some yoyos.

Normally I would have had a trellis in place here, but that’s one thing I didn’t rebuild for this run. I’m still not 100% sure if it was the lower watering frequency or if the weight of the buds just became too much, but I swear these branches are much weaker than they were when I left.



The girls are really starting to smell with the OC taking on a strong citrus profile. Hopefully they’ve recovered today after switching the timer back because I really need to defoliate one more time to open up the OC more.


Interesting result with the timing change. Im glad it wasnt worse. Actually, they dont look all that bad in the pics.

It makes me wonder if you could get by with slightly longer off times than the normal 1 minute?

I Like those yoyo’s!

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While the plants weren’t too bad, there were no white roots showing last night. Normally I see inches of new white roots daily, before they get stained by the nutes.

I am 100% sure I am not dialed in here. I had switched to the 1m OFF when the girls were showing serious signs of under-watering early on. I tested a few other variations (2s ON, 2m OFF – 3s ON, 3m OFF – etc), but I never really got exactly what I was looking for. I believe the other issues I had were causing me to adjust the wrong thing, though, so next time around I’ll be running clean clones either direct from seed or straight out of the aerocloner. That should really help me get things dialed in.


Early Problems in the System

As I said I had ran into a lot of problems early on with the system. I had planned on breaking this out separately but I realized it was too hard to determine what was caused by what, so I will go ahead and lay them out here one by one with the final changes I made to get me through this run.

Purple Stems
When the plants were very young we noticed the stems had turned entirely purple. More purple than I had ever experienced before. Magnesium was the suspect, but I knew my water / nute mix was balanced because I have grown monsters with this same solution before.

What I determined was I was having problems keeping the pH balanced, causing nutrient lock-out. Since I was using a small res and still tweaking the timings with D2W I was going through a lot more water changes than normal. With no recirculation and low EC for the clones I was having a hell of a time keeping the pH in check.

Droopy Leaves
My initial timing had me running 3s ON and 5m OFF – but the girls were showing severe underwatering. Going much higher flow rate helped eliminate the problem, but that also caused more water use than I had expected. The small res was needing filled daily at this point.

High Root-Zone Temps
One day when checking on the roots I opened the lids and it literally felt like a sauna in there. I went ahead and bought some thermostats with remote temp sensors so I could monitor things closer.

I was surprised to find that the root zone was running nearly 20° hotter than the room itself! Since the grow beds are well insulated and sealed I figured the only thing I could do would be to cool the water down, which in turn would cool the root zone.

Excessive Water Usage
With everything else going on I found that the D2W was just becoming annoying and I was having to manage water a LOT more than I ever did with my E&F setup. Instead of checking water once every 3 days I was having to check things 2x a day. This wasn’t going to work the way I had expected, so I needed to find a solution.

The Changes

In an effort to solve multiple problems at once I went ahead and picked up a chiller and decided to make the lower 1/4th of the grow beds into an ebb and flow setup.

I still had the old submersible pump from my previous iteration and my loop siphon was still in tact so what I ended up doing was feeding from the submersible through the chiller, then splitting that out into feed hoses into each grow bed. I filled the bottom portion of the beds w/ hydroton to help retain some water (and lower the amount of water required to hit the siphon).

The drains from the grow beds were then rerouted, instead of draining off to waste they would instead converge into my siphon and feed back into the res. Since I was going to have more water flowing I also swapped out my small res with the larger res I used last time.

These changes helped me get root temps under control via the chiller and recirculating water, eased the burden of managing pH by giving me a larger volume of water to balance, and allowed me to switch to a 1s ON/1m OFF cycle w/o fear of losing the water to waste.

Next Steps

I’m still not 100% sure which route I’ll take with my next run yet, but I will not be going back to D2W. Right now in my mind there are 3 ways I can run this next time around.

HPA Only
With some of the changes I’ve made and lessons learned I still think full HPA is possible. By running the drains direct back to the res w/ no siphon I could keep the benefits of a larger res and hopefully be able to keep pH in check. My only concern here is the underwatering problem I ran into.

Keeping the system how I have it today with the lower portion filled with hydroton and the upper 3/4 running true HPA. I need to reroute some fill/drain lines and make a few other changes, but this eliminates the fear of underwatering by letting them heavy feed from the lower portion while getting great nutrient uptake in the upper portion of the roots.

In this type of setup I would run a film of water down the 4 walls of each grow bed and since they are actual sinks it keeps the film straight down the drain. Then the middle of the beds would be HPA, but the plants could heavy feed off the bottom film once they reached it. (And I could set this up on a separate timer, if I wanted.)

Additional Updates

There’s a few things I have went ahead and purchased for the next run, knowing I want to change some things. First up is the way I have the water cooler plumbed into the system. Right now I’m running my nute soup through the chiller and to the plants. In the future I will add a second separate res w/ it’s own water. That will use the submersible pump to feed through a chiller coil that is submerged in the nutrient res.

Since I will be scavenging my submersible pump I went ahead and picked up the parts I’d need to eliminate the pump in the nutrient solution. I was also having issues w/ small roots being flushed back and clogging up the filter bag, or having to stick my hand down in the soup to change the speed of the pump. I picked up a controllable external pump for my needs as well as all of the filters I would want in-line. This will cover me if I do decide to keep the E&F or NFT systems in place next time around.

The two filters I picked complement each other (40 and 100 micron screens) and contain external cleanouts to help keep the system in tip-top shape.

While I was picking up parts I also upgraded my air pump to a stronger one. The previous pump would bubble the water slightly, but this new one churns the water like it’s boiling – way more air getting mixed into the solution.

When this run is completed I will be looking closely at the roots to help me decide which route I want to take next, but no matter which way I go I have all of the parts on hand to change over and restart. :seedling: