Trying to control my watering amount more precisely

[phxazcraig]

I'm setting up a 4x4 tent for another grow with Coco Coir. I'm trying to solve a problem I've had in previous grows with my watering amounts.

I've been using a 33 gallon drum with a water pump at the bottom to feed nutrients to my plants up to every 2 hours in a drain-to-waste system. I've been using a timer that allows me to program 12 cycles of varying times through the day, and it just turns the pump on for x seconds as programmed. The problem is that I get 3x the amount of water when the reservoir is full than when it is getting empty (2-3 days). I would like to pump a designated volume of water each cycle instead of just turning a pump on and off on a timer. I have two general ideas of how to address this, but I need help or a product to make these ideas work.

First idea: Measure and control the volume of water by shutting off the pump when the correct volume has been moved. I think this could be done either with some sort of positive displacement pump that can be programmed, or some sort of flow meter that can trip a shutoff to pump when the volume has been moved. (There, I don't know how I'd turn the pump back on again later though.) So far I've seen some industrial products for high pressure with high prices, but nothing for a little hobby grow.

Second idea: Maintain the same water level in the reservoir so the pump always sees the same pressure. I'm thinking here of using a second 15 gallon container and a second pump to pump water from one container to the next, controlling the pump via some sort of toilet-tank-type float valve. It's the off-on control I'm lacking here too.

Any ideas? For now I'll just set things up with a timer like before. I can't be the only one with this sort of issue.

 

[LoveGrowingIt]

That's an intriguing problem. So, the water pressure varies based on the depth of the water. Is the drum standing on end? If so, laying it sideways would reduce the difference in the height of the water (known as "head pressure") and thus reduce the variance. Another idea is to add a second tank with a float valve in it. The pump would then fill the smaller tank until the float valve shut it off. Then that measured amount of water from the second distribution tank would be released to the plants, possibly working like a toilet tank.

 

[Zill]

Hey Phx,

Are you drawing the water out the bottom of the drum? I know you said you were pulling from the bottom but out the bottom of drum or do you run a line from the bottom back up through the lid?

Run a line back out the drum it will make pump work harder and sort of even out the performance.

 

[LoveGrowingIt]

Are you drawing the water out the bottom of the drum? I know you said you were pulling from the bottom but out the bottom of drum or do you run a line from the bottom back up through the lid?

Run a line back out the drum it will make pump work harder and sort of even out the performance.

If I understand correctly, I believe doing so would create a siphon, and once created the pump wouldn't have to work harder if it's below the water level in the tank. I'm not sure it would even out performance, though, because the water pressure at the input to the pump would still depend on the water level in the tank.

 

[Zill]

Yup, the weight of the water column. Can you add an automatic water fill? Float valve on/off.

 

[phxazcraig]

That's an intriguing problem. So, the water pressure varies based on the depth of the water. Is the drum standing on end? If so, laying it sideways would reduce the difference in the height of the water (known as "head pressure") and thus reduce the variance. Another idea is to add a second tank with a float valve in it. The pump would then fill the smaller tank until the float valve shut it off. Then that measured amount of water from the second distribution tank would be released to the plants, possibly working like a toilet tank.

If I tip the drum over all the water will spill out...
On the other idea, perhaps reread what I wrote.

 

[phxazcraig]

Some of you are on the right track. I've been trying to figure out a '2-tank method', because I have 2 tanks, basically, a 15- and a 33-gallon one. But all the ideas I had about measuring water or using floats or some electronic controls were basically too complicated. Plus I've got seeds sprouting so have to get this solved rapidly.

And I had a workable idea late last night which I think works perfectly, in theory. I use a smaller tank with the pump in it, and a bigger (33-gallon) tank to feed it. Rather than try to balance input with output here, I thought about this: Hang a bucket over/inside the big tank, and put the pump in the bucket. The big tank would be filled as usual, and I would simply run a line out of the recirculating pump I already use in the big tank into the overhead bucket. I don't worry about floats or anything like that, I simply allow the recirculating pump to overfill the bucket and have it overflow back down into the big tank. Small bucket stays filled so that pump sees constant head pressure. (Or at least repeatable every cycle). I would probably arrange some sort of drain line to make things less messy, but this system has simplicity going for it. Nothing has to be measured more than I'm already doing with the pump timer. Plus it uses equipment I already have but more effectively.

I just need to figure out a good way to do the 'upper bucket' thing. I'm not seeing a good way to make use of the 15-gallon drum as it's just too big and tall. Plus I don't want to put a drain hole in the side. But a 1-3.5 gallon bucket hanging down inside the 33-gallon drum might just work fine plus be easily accessible for maintenance. I have to have enough capacity in the feed bucket to feed four Coco Coir pots every 2 hours. A 1-gallon bucket filled partway full likely is too small to feed without running dry.

 

[Zill]

Phx,

Can you send a simple pencil rendering.

 

[LoveGrowingIt]

If I tip the drum over all the water will spill out...

Ah... Well... It must not be like drums I've seen.

On the other idea, perhaps reread what I wrote.

It's difficult to understand. Posting a picture and/or a diagram would help.

 

[phxazcraig]

Ah... Well... It must not be like drums I've seen.


It's difficult to understand. Posting a picture and/or a diagram would help.

Hmm. This should be simple to visualize. There is a hint in this old thread from when I solved a siphon issue: https://www.thcfarmer.com/threads/c...eed-systems.126629/?post=2777670#post-2777670

If you search for PHXAZCRAIG, you will find my long thread about my first Coco Coir grow which shows a lot of the grow. It is title Explosive Growth in Coco Coir. I actually had to swap out my grow tent for a taller one during the flower stretch as I ran out of space. (22 ounce yield from that grow.)

It's like this in the 'water closet'. There is a 30-gallon drum in a closet next to the grow tent. This is the drum: (https://www.uline.com/Product/Detai...de=WB0298&gadtype=pla&id=S-24088&gad_source=1)

At the bottom of the drum I have a pump on a timer that feeds the plants inside the grow tent via a long tube. Also in the bottom of the tank I have a small water pump just circulating water. I also have an air bubbler for the same purpose, but when I went from a 15- to a 30-gallon reservoir I thought the bubbler was inadequate. I also have pH and temperature sensors for my pH controller.

The basic setup was taken from cocoforcannabis.com instructions.

The water height in the drum when full is about 25 inches, and only about 4 inches when empty. Anyone who has siphoned water into a bucket knows how much that slows down as the bucket fills. The pressure difference is probably about 1psi. I found a web site that explains the tech issue pretty well here: https://www.aquarium-pond-answers.com/2011/09/head-pressure-in-aquarium-and-pond.html

I have a hard time finding the psi rating for small impeller pumps, but I did find a $55 pump (Coralife) that says it pushes 7psi, which sounds like it is a lot more than the $10 pumps. Point is, on the cheap pumps that 2-foot difference in water head height makes a massive impact on the flow rate as the reservoir empties. I refill the reservoir about twice a week with about 10 gallons of nutrients. I mix a different ratio of nutes weekly, per appropriate charts from the nute vendor.

It is a drain-to-waste system, which takes fresh nutes in a reservoir, pumps them to the coco pots, and a separate drainage pump gets the water out of the tent and into buckets. Those buckets of used nutes are used to fertilize plants all over the house and yard. I see things flowering that never did anything before.

 

[phxazcraig]

OK, conceptually I'm homing in on something I can actually build and do it cheaply and still work. I have a 5-gallon plastic bucket that I need to basically suspend at the top of my 30-gallon reservoir. Right now I'm trying to think of a good way to support the bucket. If it is inside the reservoir and the reservoir is full, the bucket will try to float up a bit, so I'll either have to keep it higher than water level or add weight to the bucket. I may try to simply hang the bucket inside the closet using the clothes hanging rail that is already there. I will hole-saw a 1 inch hole to the upper part of the bucket, add a grommet and a drain hose back into the reservoir. I could also turn the other reservoir (15 gallon plastic drum) upside down next to the 30-gallon reservoir and just stick the bucket on top of it. I have that set up now, but I'm assuming sooner or later something will leak or overflow, and then I would want it over the reservoir. One reason I like the idea of a drain line is that it allows me to still mostly cover the reservoir top and just run the drain though the crack.

Hmm. Yep, I think this is certainly a kludge, but I think it's going to actually work out. Whatever the pump is set to, should always start with the same water head pressure (basically a few inches), so it should be completely repeatable in terms of actual amount. And since I mark my buckets with gallon marks, it will be easier than before to see how much water I'm putting in with each cycle.

Now I need to find a chain to hang that bucket from.

 

[LoveGrowingIt]

Theoretically, this is a volume problem, not a pressure problem. So, the question is this: How to distribute a specific and repeatable volume of water when water pressure is variable?

Toilets do that, so that method is known to work. A variant could be to substitute the flapper valve with a solenoid-operated valve. So, envision a measurement and distribution tank with a float valve that would fill itself when emptied and thus be ready when the next watering event occurs. The refilling would be mechanical. A larger source tank would be above a smaller distribution tank. The distribution tank would be full most of the time, like a toilet tank. When the time comes to water, a timer-controlled valve would be opened, and the water would drain out to the plants by force of gravity. The solenoid would close after a set amount of time. The position of the float valve would determine the amount of water distributed.

Here's a diagram. Sorry about my poor handwriting.

 

[Zill]

Look! A pencil drawing. In earlier note I recommended a float valve. Exactly what you’re showing. Done. Thank us very much.

Five gallons weights forty pounds not including hardware.

 

[LoveGrowingIt]

Look! A pencil drawing. In earlier note I recommended a float valve. Exactly what you’re showing. Done. Thank us very much.

This solves the problem of distributing precise amounts of water. There certainly could be enhancements, like agitators, aerators and a way to regulate the flow rate from the distribution tank. This design could be constructed of ordinary hardware store materials, except for the valve at the bottom of the distribution tank and the timers to operate it. If the supply tank is too high to lift water, a pump operated by the float could be used to fill the distribution tank. Gravity, however, is both inexpensive and quite dependable.

Five gallons weights forty pounds not including hardware.

Yes. It weighs about eight pounds per gallon for fresh water. The OP has a 33-gallon drum that could be used. It would weigh close to 300 pounds when full. I don't know how he mixes and fills it. I recommend making a stand with ordinary construction lumber and hardware.

 

[phxazcraig]

A detail here - I'm calling it water, but it's more. It's my nutrient reservoir, and I mix up and add new nutrients 10 gallons at a time, by hand. It's not tap water either, it's RO water from the kitchen downstairs. I take about 2-3 days to fill up 3 buckets with RO water, then I put a big tub on a counter, add the buckets of water and mix in nutes. Then I siphon the nutes back into a bucket, carry to the bedroom and dump into the reservoir. That part is not very automatible. I'm also using a halo watering system that I don't think will work with gravity, I need a pump. Yes, it's a repeatable (and adjustable) volume thing, but by far the easiest automation I have available is a pump on a timer. Or two pumps, one on a timer. Conceptually, if I simply had a divider right down the middle of my reservoir it would be ideal. My feed pump on one side, and the recirc pump on the other. Set up to overflow back into the other side, where of course I have the recirc pump and where I would dump in 10 gallons of nutes. If I were really into it I would cut up some plastic and silicone seal a barrier in there. But every day I think of a new issue or a new way to get this done. I tried to figure a float valve into this, but I would still need some sort of pump downstream of it.

This is also completely temporary, with the reservoirs set up in a bedroom closet and a tent next to it. I grow a crop then tear down until next year. The most I've changed the room is to put two holes in a door to hang a meter.

 

[phxazcraig]

This solves the problem of distributing precise amounts of water. There certainly could be enhancements, like agitators, aerators and a way to regulate the flow rate from the distribution tank. This design could be constructed of ordinary hardware store materials, except for the valve at the bottom of the distribution tank and the timers to operate it. If the supply tank is too high to lift water, a pump operated by the float could be used to fill the distribution tank. Gravity, however, is both inexpensive and quite dependable.


Yes. It weighs about eight pounds per gallon for fresh water. The OP has a 33-gallon drum that could be used. It would weigh close to 300 pounds when full. I don't know how he mixes and fills it. I recommend making a stand with ordinary construction lumber and hardware.

It's actually a 30 gallon drum sitting in a bedroom closet, on carpet, upstairs. I mix my nutrients by hand in an 11-gallon tub in a nearby bathroom. To get my water I keep buckets downstairs in the kitchen where the RO tap is. As I go through the kitchen through the day, I grab a gallon here and there and dump it into a bucket. When the bucket it full, I carry it upstairs and leave it in the bathroom. It's not a fast process. I mix GH nutes per one of their schedules, siphon into a bucket and carry to the reservoir. The mix changes weekly, and I have been going through about 20 or more gallons a week once the plants get big. I measure input and output EC, and it can change quite a bit over the time I fill the reservoir. I can see that less fluid is being sent in, then I can see it increase a lot when I refill. I also set two short waterings during the night, mostly just to keep the EC from spiking in the media. I'm using a pump timer 10x a day with programmable on/off to the second, so typically have a run time of 25 seconds during flower, at least with the reservoir full. Typical stuff, from cocoforcannabis examples.

As for a stand, I'm not making one, but I'm opening to kluding something together for my idea. I wish I could just buy a prebuilt system. My DIY automatic drain trays were a disaster a couple of times. There also isn't any real height work with as the reservoir is on the floor, the tent is next to it, and the plants are raised up about 6 inches up for the drain system to work. Pump it in, drain to another pump and pump it out. I'll post a pic I just took on my phone.

 

[phxazcraig]

Above is my 30 gallon drum with the 15 gallon next to it, upside down. I've got a 5 gallon bucket on the 15. I'm considering dangling the bucket over the 30 gallon. If I put my feed pump into the bucket, then add a drain back into the reservoir, I can use a second pump to constantly fill the bucket from the reservoir. That way I don't have to measure anything, and the feed pump always sees the same head pressure and puts out a repeatable amount.

 

[phxazcraig]

Still working this out. Hanging the bucket now seems a bad idea due to the weight, but using the 5-gallon where it is now seems OK. I just have to tap a hole in 3/4 way up. A friend was over and suggested I use a spigot tap as they have a good seal. I was thinking of a hole with a grommet and a tube sticking through. Either works, but either way I need to somehow drill a 3/8" round hole in the side of a bucket.

 

[phxazcraig]

I rigged up a system to give it a test today, and it worked! In concept. I put two holes in the bucket in the picture near the top edge and installed two spigot faucets. For now they are just draining back into the reservoir, but I intend to attach drain hoses to channel the outflow back into the reservoir.

But I added some water to the system, and fired up the two pumps. The pump in the reservoir pumps water faster than it drains back out, so I need to fix that. (New parts on order). The pump in the bucket fed water to the tent just fine, and after I fixed a small leak, the drainage system is working too.

I need to figure out a better hose arrangement for feeding into the bucket as I have no attachment point and just threw a hose over the top edge.

In concept, it's working fine, albeit with an increased chance of leaks and problems.

 

[Trash_2002]

TLDR LOL

Just use a dry pump that can pull water from the tank and that will also pressurize it, if you want precision watering you want constant pressure, it's achievable using for example a 30psi pump for one "small" zone or a 60psi (better solution imo), on the main lines and 30psi pressures reducer per zone/tent/irrigation loop.

Than you control water flow by using different rates pressure compensated button drippers before your actual plant dripper. you can use the rated drippers to achieve your desired flow of water per time. there's 1-2-4-8L and 16L per hour button drippers afaik, after that it's only some simple math to achieve what you want.