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Sometimes the Autovalve does not behave the way it should, and if action is not taken, floods or unhappy plants can result. This thread is to present troubleshooting and fixes for common problems.
Autopot users should learn how the flood sequence operates. In particular, it is helpful to understand how the two float valves interact to cause the flood cycle to behave the way it should. Here is a video which illustrates how the valve functions:
For those without access to the video (i.e. some phones, some internet connections...) here is an image summarizing the same description of how the valve works:
Here is a video on assembly and disassembly of the Autovalve (watch this before taking your valve apart to inspect it or clean it. Otherwise, you could break something, particularly the hinge on the top float):
I don't have equivalent pictures for anyone unable to see the second video, but the most important point made in it is that the top float (the external one) should not be snapped out of its hinge during disassembly. It needs instead to be rotated upward ~90 degrees and slid out sideways. If done correctly, it comes out with negligible resistance. If it doesn't, it is not rotated to the correct position, or it is being pushed toward the wrong side.
Terms I will use here:
There are two valves in the Autovalve, one for incoming nutes/water (the Flood Valve), the other for air (the Air Valve). The terms I will use are labeled in the two photos below:
Note the shape of the valve seats - they are relatively sharp edges intended to press into the silicone pads in order to close the valve.
How the valve should operate: If the Autovalve is operating properly, it will fill the tray until the water is about 25mm deep, and not further. It will then not refill the tray until it is virtually empty. Virtually empty means that no more than a couple mm of water is left.
If your tray overfills, floods the floor, or fails to fill at all: This probably means that the flood valve is malfunctioning. If the flood valve does not seal shut, water/nutes will overflow the tray and flood the grow space and potentially the floor of the room it is in. If the valve does not shut as soon as it should, water level in the tray will be too deep, lengthening the flood cycle and flooding the pot more deeply, either or both of which could result in overwatering and/or root problems. Causes of overfill or flooding, and their fixes are:
If your tray does not completely empty before re-filling: This is usually caused by failure of the air valve to seal. This allows air into the cover, causing the water level inside to drop and opening the flood valve prematurely. This will result in cycling between a full tray and something like half empty rather than between full and empty. This will prevent the bottom of the flood zone from aerating completely with each cycle, potentially causing overwatering or problems with roots.
If the air valve is plugged, or stuck closed, or if the twin floats are full of water, air will be prevented from leaving the cover as water rises, potentially preventing proper closing of the flood valve.
All the specific issues and cures listed above for the flood valve apply to the air valve. One difference between the air valve and the flood valve is how each is disassembled - the air valve float is removed by sliding sideways, not by snapping it out of its hinge points, a critical point made by the video above.
One other potential cause of cycling before the tray empties is a cracked flood valve cover that allows air to get inside even when the air valve is sealed. Unlikely, but possible, and potentially curable with some epoxy or caulking.
If you are not sure your valve is behaving properly, find out by doing this: It can be tough during a grow to know whether your valve is behaving. The water level changes slowly, and if you don't happen to catch it when the tray is nearly empty, you may not know if it ever gets there. Valve operation is easily tested by manually removing water from the tray until it starts to re-fill. A turkey baster works. As the water level gets close to the floor of the tray, remove water slowly, and you will see and hear when air finally gets sucked into the float valve cover beneath its lower edge, and the water in there gushes out, opening the flood valve. This will not happen before the nute mix is almost at the lower edge of the cover if the air valve is operating properly. lf the re-fill starts when there is still ~~10 or so mm of water level in the tray, the air valve is leaking, or the cover is cracked. Watch the refill until filling stops. If the flood valve is operating properly, the water level will stop somewhere around 25mm or so deep. The exact level varies a bit between valves, but not by a lot. If valve function is not correct, turn off the water, pull the valve out, disassemble it completely and clean everything. Re-assemble carefully making certain that silicone pads are fully seated, and re-install. If there is junk in the valve area of the tray, clean it out before re-installing the valve - a shop vac works a treat for this. If you do not have spare silicones, do not do this in a sink - silicones have a habit of finding drains.
Happy autopotting peeps.
Autopot users should learn how the flood sequence operates. In particular, it is helpful to understand how the two float valves interact to cause the flood cycle to behave the way it should. Here is a video which illustrates how the valve functions:
For those without access to the video (i.e. some phones, some internet connections...) here is an image summarizing the same description of how the valve works:
Here is a video on assembly and disassembly of the Autovalve (watch this before taking your valve apart to inspect it or clean it. Otherwise, you could break something, particularly the hinge on the top float):
I don't have equivalent pictures for anyone unable to see the second video, but the most important point made in it is that the top float (the external one) should not be snapped out of its hinge during disassembly. It needs instead to be rotated upward ~90 degrees and slid out sideways. If done correctly, it comes out with negligible resistance. If it doesn't, it is not rotated to the correct position, or it is being pushed toward the wrong side.
Terms I will use here:
There are two valves in the Autovalve, one for incoming nutes/water (the Flood Valve), the other for air (the Air Valve). The terms I will use are labeled in the two photos below:
Note the shape of the valve seats - they are relatively sharp edges intended to press into the silicone pads in order to close the valve.
How the valve should operate: If the Autovalve is operating properly, it will fill the tray until the water is about 25mm deep, and not further. It will then not refill the tray until it is virtually empty. Virtually empty means that no more than a couple mm of water is left.
If your tray overfills, floods the floor, or fails to fill at all: This probably means that the flood valve is malfunctioning. If the flood valve does not seal shut, water/nutes will overflow the tray and flood the grow space and potentially the floor of the room it is in. If the valve does not shut as soon as it should, water level in the tray will be too deep, lengthening the flood cycle and flooding the pot more deeply, either or both of which could result in overwatering and/or root problems. Causes of overfill or flooding, and their fixes are:
- Silicone pad is missing - Make sure the pad is still in place. Pads can fall out when the valve is being handled, and if this is not noticed, a flood will result when water is turned on.
- Silicone pad is misaligned - Seat the pad fully and squarely into its retainer cavity. The exposed seal surface should be level with the rim of the retainer cavity. This photo shows a properly seated pad, and one that is not. Any debris in the retainer cavity could prevent the pad from seating properly, so make sure that the retainer cavity is clean before seating the clean pad.
- Silicone pad is distorted or damaged - Replace a damaged pad, reverse a distorted one if doing so provides an aligned and smooth seal surface. When the valve operates and the pad is squeezed against its valve seat, a slight groove will develop in the seal surface of the pad. If this is changed in alignment for any reason, it can result in the valve failing to seal. Debris caught against the silicone pad could also dent the pad so that it no longer seals even when clean. The cure can be to simply reverse the pad so that the distorted surface is inside the retainer cavity and a fresh smooth surface is presented to the valve seat. Distortion of pads can also happen during storage. The safest storage is to remove all pads from your valves, clean them, and store them dry in a zip lock bag, making sure that nothing is sitting on them or pressing against the bag. Pads can also be damaged, particularly during attempts at cleaning or clearing the valve. Do not use abrasive pads of any kind to clean the pads, soft cloth and water are all that are required. If a pad becomes encrusted in hard material that will not easily come off, replace it. Having spare pads is a good idea. A silicone lost down the drain could seriously bugger a grow.
- Silicone pad, or valve seat are contaminated or dirty - Clean them. The valves will not seal if junk is embedded in the silicone pad or sitting on the valve seat. Keeping soil particles out of the valve area is important. They can float around inside the flood valve cover and become trapped between the valve seat and silicone pad, and once in there, they may stay put and cause leaking. It pays to turn the water off a few times during a grow, pull the valves and clean clean them, and clean the valve area to remove any soil particles or other debris.
- Float hinge on the flood valve is dirty, damaged, or misaligned - make sure that the hinge is free to rotate without jamming or sticking. If the hinge is damaged, replace the Autovalve.
- Valve seat is damaged - replace the Autovalve. Damage can happen during ill advised attempts at cleaning the valve with metal tools. The valve seat has a fairly sharp rim intended to press into the soft silicone pad. This sharp rim is easily gouged or dented by any kind of hard tool. Bottom line, never try to clear the input line or valve with anything as hard as or harder than the plastic of the valve. If either valve seat is damaged, the entire valve is toast.
If your tray does not completely empty before re-filling: This is usually caused by failure of the air valve to seal. This allows air into the cover, causing the water level inside to drop and opening the flood valve prematurely. This will result in cycling between a full tray and something like half empty rather than between full and empty. This will prevent the bottom of the flood zone from aerating completely with each cycle, potentially causing overwatering or problems with roots.
If the air valve is plugged, or stuck closed, or if the twin floats are full of water, air will be prevented from leaving the cover as water rises, potentially preventing proper closing of the flood valve.
All the specific issues and cures listed above for the flood valve apply to the air valve. One difference between the air valve and the flood valve is how each is disassembled - the air valve float is removed by sliding sideways, not by snapping it out of its hinge points, a critical point made by the video above.
One other potential cause of cycling before the tray empties is a cracked flood valve cover that allows air to get inside even when the air valve is sealed. Unlikely, but possible, and potentially curable with some epoxy or caulking.
If you are not sure your valve is behaving properly, find out by doing this: It can be tough during a grow to know whether your valve is behaving. The water level changes slowly, and if you don't happen to catch it when the tray is nearly empty, you may not know if it ever gets there. Valve operation is easily tested by manually removing water from the tray until it starts to re-fill. A turkey baster works. As the water level gets close to the floor of the tray, remove water slowly, and you will see and hear when air finally gets sucked into the float valve cover beneath its lower edge, and the water in there gushes out, opening the flood valve. This will not happen before the nute mix is almost at the lower edge of the cover if the air valve is operating properly. lf the re-fill starts when there is still ~~10 or so mm of water level in the tray, the air valve is leaking, or the cover is cracked. Watch the refill until filling stops. If the flood valve is operating properly, the water level will stop somewhere around 25mm or so deep. The exact level varies a bit between valves, but not by a lot. If valve function is not correct, turn off the water, pull the valve out, disassemble it completely and clean everything. Re-assemble carefully making certain that silicone pads are fully seated, and re-install. If there is junk in the valve area of the tray, clean it out before re-installing the valve - a shop vac works a treat for this. If you do not have spare silicones, do not do this in a sink - silicones have a habit of finding drains.
Happy autopotting peeps.
Last edited:
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