Like a lot of longtime dope growers, I'm a slacker. I don't want to have to muck around with my grow op every damn day. Topping up reservoir tanks and setting pH every few days is a pain.

No worries- it's fully possible to automate the process using lawn irrigation bits.

My 'vacation' (or 'slacker') watering system is a 125 litre tank, set up on concrete blocks so the bottom of the vacation tank is above the top water levels of the flood tray rez tanks. This way, the vacation tank water gravity feeds down into the main tanks through a float valve mounted in each tray rez tank.

However, if the vacation tank was allowed to refill the tray rez tanks at ANY time the tray rez tank levels dropped below the float valves- as they do every time the trays are being flooded- the tray reservoirs would overflow and spill on the floor when excess water is drained back from the trays.

The solution is a battery operated digital lawn irrigation timer valve ($10 @ dollar shop) which is mounted to the bottom of the vacation tank. The timer valve is then connected with sections of old garden hose and 'tee' fittings to a float valve in each of the rez tanks.

With the timer valve, even though the individual tray rez levels do drop below the float valve levels when flooding the trays, the tanks are not refilled right then.

The timer valve is programmed to open and refill the rez tanks to float valve levels a couple hours after the trays are flooded, when excess water pumped up into the trays has fully drained back into the individual tray rez tanks.

While the vacation tank can be refilled with plain tap water, I have also hung my dehumidifier from the ceiling of the grow room, putting it above water level of the vacation tank. The dehumidifier puts out about 8-10 litres of mineral and chlorine-free distilled water every day, which is usually enough to keep the tray rez tanks fully topped up between bi-weekly rez tank dumps.

The pH of the dehumidifier water is about 6.2-6.5, so I pH correct the vacation tank down to 5.8 every few days, but it can be left alone if need be. The plants don't mind the pH being a little bit high compared to how much they would care about running dry!

The tray rez tanks are about 5.8 right after I have mixed up fresh tanks of sauce with tap water and Canna nutes- Canna must put pH buffers in the nutes as I never have to pH adjust immediately after mixing up fresh tanks of sauce. The pH of the tray rez tanks also stays right about 5.8 throughout the 14 day life of a mixed tank of nutes as they are being topped up with pH adjusted plain water from the vacation tank.

I don't put any nutirent in the vacation tank. If I did, the individual tray rez tanks' nute strength would jump up as water evaporated from the system.

Aside from pH correcting the vacation tank, I do put about 50ml of 50% hydrogen peroxide into the vacation tank (and the rez tanks) every 3-5 days to kill off pathogens. Can be done bi-weekly if I'm really slacking, though.

With this arrangement, if I want to, I can leave the entire system unattended for up to 2 weeks at a time. However, I do usually feel like messing with it a little more often than that (but not much more)!

Anyone should be able to duplicate this setup. Happy to answer any queries you may have about it.

if you dehumidifythe room won th the plants dry out.

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"All stupid people should be shot in the head. Thin the heard people its called nature" -adam corolla

http://www.rollitup.org/grow-journal...xperiment.html

Nope- the plants are constantly transpiring water through their leaves, adding to the humidity in the room. There's also a fair amount of evaporation directly from the rez tanks and pots of rockwool. My dehumidifier is not big/powerful enough to remove ALL the water put into the air from various sources. Even if it was, it has a control knob which I can use to dial-in the humidity to a particular level.

The dehumidifier keeps the room humidity at about 30-40%, great for the plants but not so good for mould, fungi, powdery mildew etc. It's probably one of the best purchases I've made for the op.

A dehumidifier is especially helpful for lights-off hours in wintertime. It adds a little heat to the room just by sitting there running. Cool temps coupled with high humidity is a recipe for a powdery mildew disaster.

Where in the op is the vacation tank located? What do you use to keep it elevated and where is it in relation to the plants?

Edit:
Also, will the PH of your water change just from sitting around for extended periods of time?

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16 SHIVA SKUNK CLONES / 600w HPS

Very cool man...exactly what I was looking for. Smart setup.

The catch tank is actually outside of the flowering area. Just wasn't any room in there for it. It is up on concrete blocks (per post #1) so that the bottom of the catch tank is above the top level of the tanks it feeds, such that gravity is all that is needed to top up the tanks, yet below the catch tray within the dehumidifier. Float valves set the levels in the nute tanks.
No, water coming out of the dehumidifier is 7.0 (when you measure it with a pH probe in working order- I cited 6.2-6.5 in post #1 due to a faulty electrode on the pH meter, since replaced) and stays there. However, if the tank is colonised by fungi or other pathogens, that can change the pH. The catch tank doesn't have any nutrient in it but has to be cleaned every couple of weeks anyway. Pathogens will live in plain water too, but they really like water with nutes in it of course.

I only run this system when I am going to be away. When setting it up on the day I'm leaving, I start with a full catch tank, which I dose with H2O2 @ 1ml/L and then I pH adjust it to 5.5. The 7.0 water coming into the tank from the dehumidifier in coming days will progressively raise the pH. The nute tanks' pH will also bump up over several days all by themselves due to trace amounts of limestone in the rockwool floc used in the bottom of each pot.

If the nute tanks are at 5.8 on the day I leave, the 5.5 water from the first couple times the catch tank refills the nute tanks will keep them pretty much around 5.7-5.8. However, after a week or so unattended, having been constantly refilled by the dehumidifier, the water in the catch tank is is close to 7.0 and will be pushing the nute tanks' pH up, too.

I don't have any automated means of maintaining pH in either the nute tanks nor the catch tank. The pH does swing high after about a week and the system is intended to run for about 2 weeks unattended, but it's better than the system running dry. The vacation system isn't needed for unattended operation of less than a week, but has saved my bacon on two occasions where I was hospitalised and had no one to mind the system.

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Get a harvest every 2 weeks - A batch of clones in rockwool - Al B. Gone

i like your idea here. when i eave the spot i will def make one of these. should i put a dehumidifier in my flowering room?

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Jerk it in my attic...