# 'overflow preventer' / water contact = auto power out



## Andrew Butler (1 May 2020)

As usual not the best of descriptors from me!

Looking to add a discrete probe/sensor to my AIO (All In One) aquarium; just as an added safety feature really.
I'm just looking for a bit of extra info and mainly anyone with some suggestions for a probe I can use for the project and suggestions of systems are welcome. Discretion is the word so something that acts instantly, is small, compact, I could hide easily etc is key for the probe so rule float valves out straight away; I'm also not keen to have something with a light on the sensor as my AutoAqua Smart ATO Micro has.

I know there's a few types of option but interested to hear what people have to put forward and given the initial idea is nearly 10 years old now, things have probably changed with product choices and possibly affordable technology. (I'm not looking to spend hundreds on a sensor)

Simply when/IF the water was to reach a level very close to the rim it would power out the pump; whether this be the 240 supply or something I can feed 240 straight into and it outputs the controlled requirements of the pump. The supplied power adapter is 24V 1.75A and the pump is a Jecod DCP-2500 if that helps at all.
(unsure if positive/negative etc makes a difference with this kind of project?)

The video goes in hand with a website that's down but there's pointers towards a discussion it originated from in the links too:
https://forum.allaboutcircuits.com/threads/water-sensor-power-shutoff-urgent-help-needed.50227/
https://hackaday.com/2011/04/15/aquarium-overflow-sensor-saves-your-fish-and-your-floors/
https://reefs.com/2011/04/21/diy-prevent-overflows-in-your-reef-tank/
https://www.youtube.com/watch?time_continue=1&v=9q7LxGms3DM&feature=emb_logo

Many thanks
Andrew


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## jaypeecee (1 May 2020)

Andrew Butler said:


> Discretion is the word so something that acts instantly, is small, compact, I could hide easily etc is key for the probe so rule float valves out straight away



Hi @Andrew Butler 

I made something similar to what you are talking about. I use it to switch off my external filter in the unlikely event of a water leak. But, it does use a compact, vertical float switch - not valve. If I was to design and build another, I would experiment with capacitive sensors which are located on the external side of a glass panel. I seem to recall that _Honeywell_ has some interesting options.

JPC


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## Andrew Butler (1 May 2020)

jaypeecee said:


> I would experiment with capacitive sensors which are located on the external side of a glass panel


Thanks for the input @jaypeecee - a job for tomorrow I think.


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## Fisher2007 (2 May 2020)

Have a look at marine fish tank auto top up systems

When I had my marine tank it evaporated 5+ litres per day in the summer so I had one.  The one I had was a very small float valve and an optical sensor.  The sensor would detect the drop in water and turn the pump on and the valve would turn it off once at the required level

It's been a few years since I've ran one but having just looked on Google similar are still available and no doubt better versions.  I'm thinking you could use it to do the opposite and turn a pump off if the level got too high.  If you were to use the optical sensor alone it would be really discrete.  The sensor I had was maybe half an inch wide by 1 inch long and it sat above the water line


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## Andrew Butler (2 May 2020)

Fisher2007 said:


> Have a look at marine fish tank auto top up systems
> 
> When I had my marine tank it evaporated 5+ litres per day in the summer so I had one.  The one I had was a very small float valve and an optical sensor.  The sensor would detect the drop in water and turn the pump on and the valve would turn it off once at the required level
> 
> It's been a few years since I've ran one but having just looked on Google similar are still available and no doubt better versions.  I'm thinking you could use it to do the opposite and turn a pump off if the level got too high.  If you were to use the optical sensor alone it would be really discrete.  The sensor I had was maybe half an inch wide by 1 inch long and it sat above the water line


They tend to be targeted for use in sumps, however I know there are more aimed at the display themselves now and have some already.
I had a 2 step type ATO (Osmolator according to Tunze) with my marine also but it's just too big and unsightly for what I want when a small piece of black acrylic to match the filtration partition could hold it all and be just as reliable.

There's all kinds of them available and I have some optical ones which are nice and small, the one I mentioned is the AutoAqua Smart ATO Micro. This is exactly what I looked at doing and although whilst electrically possible it still leaves me with quite a bright light and it would continually be beeping and flashing as it wouldn't be within its range. I'm sure there's more thinking that could be done on that but if there's a simple sensor that exists then my not use it?

AutoAqua smart level security is a product that is just that BUT it doesn't exist in the UK plug type, I could import one but would be costly just to rip a system apart.

There is a very simple product intended for blind or partially sighted people when filling cups that beeps to alert of water levels, often called a liquid level indicator. It works by simply having 2 pieces of metal that when the water makes contacts completes a circuit which is likely the way I'll be looking unless I get any more input.

Input for the above 'liquid level indicator' type system is very welcome with regards to suggested circuits that would simplify things and keep safety in mind. Maybe there's that product already out there to do away with all the thinking etc that's NOT a float valve!

Thanks
Andrew


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## dino21 (2 May 2020)

We use one of these Infra Red level sensors, ( no visable light ) keeps the level to around  1mm as an ATU  but could equally be used as an overfill sensor.
Its mounted on some clear plastic/perspex  so not really noticable, but that depends on your view.  The IR fittings flange outside diameter  is  just 21mm

Have also tested  these out of tank sensors and again surprising accurate though more 3-4mm.

Both are 5v working and will need some interface board /control unit for them to be of use.







Edit,  Seems you can now get them with a control board and relay all ready to run, expect one like this cold be wired to act as you want.

https://www.ebay.co.uk/itm/Dual-Sen...rand=Unbranded&_trksid=p2047675.c100005.m1851


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## Andrew Butler (2 May 2020)

thanks @dino21 how long is the cable on the sensor?
Optical is also something I have in mind but at 21mm would be too big to allow a smaller margin than 10mm from rim which is about where I want to have my normal water level and that's assuming it was tight to the rim.
I am interested to see some more details/pictures of your system though.
Thanks
Andrew


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## Andrew Butler (2 May 2020)

@dino21 I'm finding things like small, discrete float valves in stainless steel after following your link which is a product I can live with and MAYBE if I find a very small one in black that would tip me that way in the consideration list.
https://www.ebay.co.uk/itm/Stainles...rand=Unbranded&_trksid=p2047675.c100005.m1851


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## dino21 (2 May 2020)

Andrew Butler said:


> @dino21 I'm finding things like small, discrete float valves in stainless steel after following your link which is a product I can live with and MAYBE if I find a very small one in black that would tip me that way in the consideration list.



Have you seen the size of that float, plus you will need a guard around it to stop the plants and snails obstructing its movement ... ?






The Optical sensor I have is approx 45cm long and as you can see below, if you want a water level of 10mm thats about the same distance as its tip to  its hole mount position so you would just need a flat mounting plate across the top edge of your tank.

However the pic  shows the current sensors on offer  that use a back nut /thread whereas mine are a front nut and thread , so cannot say exactly what their measurement are, but doubt they are that much different., but looks like plenty of thread for adjustment of a few mm.  Ours has been in use for over a year. so an earlier model.

Would have thought the  Non-contact liquid level sensor which could be mounted out of site on the outside back of the tanks glass would have been a better choice ?


If you do not mind me saying ,  think a water level of just 10mm is always asking for trouble ...?  assume your base/stand  and floor are rock steady  and what about tank cleaning and  trimming the plants etc  where you have to put your hand and arm in ?
Similary is it not also inviting the fish to jump over  ?


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## jaypeecee (2 May 2020)

Hi Folks,

I don't know that I'd feel entirely comfortable using the optical sensor type. I assume these are the ones that rely on total internal reflection, which is then interrupted when the sensor tip is in contact with water. Do they work reliably if the water surface has an oily film on it or even a drop of water on the sensor tip itself? That's why, when I last looked at this, I was moving towards external sensors of the capacitive type.

JPC


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## dino21 (2 May 2020)

jaypeecee said:


> Hi Folks,
> 
> I don't know that I'd feel entirely comfortable using the optical sensor type. I assume these are the ones that rely on total internal reflection, which is then interrupted when the sensor tip is in contact with water. Do they work reliably if the water surface has an oily film on it or even a drop of water on the sensor tip itself? That's why, when I last looked at this, I was moving towards external sensors of the capacitive type.
> 
> JPC



Have used our optical one for over a year now and its kept things spot on for ATU. Its housed in  about 40mm of plastic tube to keep the plants off it and to reduce any 'wave' effect,  though do find the odd little snail in there, it does not seem to affect things.
The ATU bottle is sized so that even if things failed and it pumped the full bottle up, it cannot cause and overflow.
Have always used a surface skimmer, so not sure about an oily film ...?

We purchased an external capacitive one at the same time as the optical  and tested them both, the external does seem to need a 3-4 mm difference to register a change, which is ok for an overflow sensor, but it needs a really good adhestive to hold it onto the glass, which could make level adjustment difficult.

Forgot to ask Andrew why he needs an overflow sensor if his All in one tank (?)  does not have a sump  ? or similarly if it has an ATU that could cause an overflow, what water sensor is it using already ?


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## Andrew Butler (2 May 2020)

jaypeecee said:


> I don't know that I'd feel entirely comfortable using the optical sensor type


I was always given that kind of thinking when I was on the salty side but I've had 3 of the AutoAqua which rely on one optical sensor and so far (he says) no failures. Keeping them clean I think is part of it . This is only a safety feature incase everything gets completely blocked off in the filtration section.



dino21 said:


> Have you seen the size of that float, plus you will need a guard around it to stop the plants and snails obstructing its movement ... ?


I had seen the size but there are smaller versions following a similar design and it's opened me upto having a tiny one that could also be a black plastic one - I was dead set against a float switch before and maybe still am a little but broadens the horizons possibly.


dino21 said:


> The Optical sensor I have is approx 45cm long and as you can see below, if you want a water level of 10mm thats about the same distance as its tip to its hole mount position so you would just need a flat mounting plate across the top edge of your tank.


You're suggesting it be mounted face down?


dino21 said:


> Would have thought the Non-contact liquid level sensor which could be mounted out of site on the outside back of the tanks glass would have been a better choice ?


This is something I've not looked into properly yet but haven't forgotten @jaypeecee suggesting it - do you have any more info?


dino21 said:


> If you do not mind me saying , think a water level of just 10mm is always asking for trouble ...? assume your base/stand and floor are rock steady and what about tank cleaning and trimming the plants etc where you have to put your hand and arm in ?
> Similary is it not also inviting the fish to jump over ?


I'm unsure what level you run your water below rim but I know it's not abnormal to run a planted rimless/braceless aquarium with such a small margin although 12mm is probably more where it ends up but I wouldn't want the sensor to be this low and more towards the surface, as I say it's a safety feature just incase the filtration completely gets blocked somehow. More to it than just this but this is the bare essentials needed to understand things I think.
My floor is a concrete one that's roughly 6 years old now so had time to settle and more than sufficient to take this kind of load, there's a compact resilient vinyl flooring on top of that and then a custom cabinet which is far more capable of carrying the load several times over.
As for cleaning/trimming; I tend to do mine at water change time, unsure what everyone else does that runs a small rim-waterline although I appreciate there are times you need to get in. I just siphon a bit out quickly and refill it afterwards if this is the case.
Jumping fish is an interesting topic and one that put me off the idea of a rimless aquarium for a number of years and when I first did used Jump Guards but as time went on learnt a bit more about what fish are more likely to jump from an open top aquarium and I guess followed suit to what many people on here do and accept there can be a casualty from time to time although I've not had this problem for a while.
*Maybe someone else can add a bit more here and offer some words about open top aquariums and minimal rim-waterline, maybe I've got it all wrong?


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## jaypeecee (2 May 2020)

dino21 said:


> We purchased an external capacitive one at the same time as the optical and tested them both, the external does seem to need a 3-4 mm difference to register a change, which is ok for an overflow sensor, but it needs a really good adhestive to hold it onto the glass, which could make level adjustment difficult.



Hi @dino21 

Thanks for the feedback. It seems very odd that the capacitive sensor needs to be attached using an adhesive _on the sensor itself_. Can they not be held in place by a good adhesive tape? Some of these will stick to fresh air - OK, not quite! 

JPC


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## dino21 (3 May 2020)

@Andrew Butler     You're suggesting it be mounted face down?

Yup, our is , works fine.
As none of those sensors are that expensive,  best get all three types and see which you find works best for you in practical and asthetic terms.

We use an external filter so no chance of internal filter blocking and causing an overflow , but still run with a 20mm level, we have wooden suspended floors.

Footnote, we used to have and intank filter system like yours for years and never had any real problems, though again we had a level low enough that if the filter did block then the pump could  not cause an overflow, 
Plus you always have a small hole low down in the pump chamber to tank so the pump cannot run dry.


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## dino21 (4 May 2020)

@Andrew Butler 

Though you are looking at an overflow preventer,  makes us think about a more fundamental approach.

Not sure if you are talking about your AIO tank from last Augusts post or if this is another one ?

You have your tank dimensions and know what that 10mm equates to in Ltrs ?

So the next question would be, if your in tank filter suddenly and totally blocked at the weir, or any point after, what volume of water could the pump remove before it ran dry.
Clearly not the whole filter contents because of the baffles,  so would that volume, if you can test  or claculate it,  be greter that what the 10mm can hold , enough to actually cause the tank to overflow ?

Assume your main filter panel is as high as the main tank walls, but if you had it all or just the  last pump section 5mm or so lower, then any excess tank water would overflow back into the pump chamber , yes ?


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## Andrew Butler (5 May 2020)

@dino21 thanks for your opinion and input but all I'm looking for is some input towards an electrical idea and respectfully not be questioned over why.


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## dino21 (5 May 2020)

Andrew Butler said:


> @dino21 thanks for your opinion and input but all I'm looking for is some input towards an electrical idea and respectfully not be questioned over why.




No problem, understand , not meaning to distract you from the sensors.


As far as the sensors go may we just add one last comment on how we used to do it or how you can do it in a similar fashion with todays modern kit.

Placing the level sensor in the pump chamber is what we did, so none of the problems with fitting it in the main tank, particularly visual.
If the level drops in the pump chamber it can be detected much earlier and more precise than a very small level change in the main tank.

The sensor you choose might be suitable for direct connection  and programmable into some of todays modern aquarium controllers, (?) but if not some simple circuity can be used.

The sensor interfaces and controls a small timer as it needs to keep the pump off for a set time once the level goes low, to allow the flow to recover and avoid any chance of oscillations.

Then you need the timer to control a relay, this not only operates the pump but also the heater, you do not want that running without circulation.

The relay or relays would also operate something like a loud piezo type sounder.


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## Andrew Butler (6 May 2020)

@dino21 I think it best I just try and answer your questions or reply to your comments.....................


dino21 said:


> Assume your main filter panel is as high as the main tank walls, but if you had it all or just the last pump section 5mm or so lower, then any excess tank water would overflow back into the pump chamber , yes ?





dino21 said:


> Footnote, we used to have and intank filter system like yours for years and never had any real problems, though again we had a level low enough that if the filter did block then the pump could not cause an overflow,
> Plus you always have a small hole low down in the pump chamber to tank so the pump cannot run dry.





dino21 said:


> Though you are looking at an overflow preventer, makes us think about a more fundamental approach.





dino21 said:


> You have your tank dimensions and know what that 10mm equates to in Ltrs ?





dino21 said:


> So the next question would be, if your in tank filter suddenly and totally blocked at the weir, or any point after, what volume of water could the pump remove before it ran dry.
> Clearly not the whole filter contents because of the baffles, so would that volume, if you can test or claculate it, be greter that what the 10mm can hold , enough to actually cause the tank to overflow ?


I'll try and work through things in no particular order.........
-my pump has '_Electronic detection of no water enables automatic power off protection'_ as a feature so running dry, I don't think is a worry for me.
-I can, and have calculated the amount of water in all compartments per 1mm (x10 = 10mm) and the answer is it would need to be far too low for my liking before even taking any kind of ATU/ATO system into account I knew this at the time of build but was under the impression that 2mm would be sufficient.
-Following on from that; I am talking about an AIO (All In One) system, which I have experimented with completely blocking my filter inlet off. Originally the main partition was installed dropped by around 2mm below the rim but when testing this clearly wasn't enough so after some deliberation I trimmed some from the top until I _had_ enough, the absolute minimum it can be is around 6mm and this is absolutely bulging to the brim with the pump on minimum power with no disturbance which an increase in power does cause. I'm not entirely happy with this and don't want to reduce the partition anymore as in my opinion it's quite an eyesore as it is.


dino21 said:


> Placing the level sensor in the pump chamber is what we did, so none of the problems with fitting it in the main tank, particularly visual.
> If the level drops in the pump chamber it can be detected much earlier and more precise than a very small level change in the main tank.


I have an optical sensor which will keep an eye on the water level in the return section and act as an auto top up but this still leaves me with the problem of what happens if _'the in tank filter suddenly and totally blocked at the weir, or any point after.' _as you question; the answer is run bulging to the brim with the pump on minimum power with no disturbance which isn't ideal or sensible in my opinion.
This is a safety feature which needs to act instantly should '_the in tank filter suddenly and totally blocked at the weir, or any point after.' - _I now hope this explains things better and why I think a sensor that is controlled by water simply acting as a switch by completing a circuit may be a good choice for me - as ever I'm interested to hear more 
A float switch ( not valve - sorry @jaypeecee ) I'm not overkeen on for various reasons and external capacitive one seems to have its flaws for this situation too; I'm looking at solutions differing to both the two just mentioned and optical that would be instant acting


dino21 said:


> We purchased an external capacitive one at the same time as the optical and tested them both, the external does seem to need a 3-4 mm difference to register a change, which is ok for an overflow sensor, but it needs a really good adhestive to hold it onto the glass, which could make level adjustment difficult.


Thanks though @dino21


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## Andrew Butler (10 Jun 2020)

A product I was hoping would become available sometime soon in the UK as you can imagine is now just delayed further so back on the hunt. Anyone with a fresh set of eyes then please give me some pointers.


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## dino21 (10 Jun 2020)

Hi,

Thinking about your problem again, then this is what we would do using an optical sensor.

To provide minimal visual presence, mount it vertically though a hole in  your main baffle, so just the face of the sensor is in the main tank.

You will ideally need to position some clear acrylic around to sensor to stop any plants leaves flowing onto it and also to calm the water down , something like one half of this float switch cover in the pic below, similar to what we use around our optical when mounted horizontally.

You can buy the sensor with a board that products a simple on /off signal,  that then feeds into a relay driver and the important  Delay timer like I mentioned before,  or you could use a little Arduino etc to connect the sensor to it directly, which could also control your ATU  etc.
Even with such control, your atu reservoir should not be that big that it could cause an overflow.

As you mention in your other post, a pair of wires/probes  etc acting as a conductor will not be practicalbe/ reliable imho, so a float switch or external level sensor are the only practical options we can think of.


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## Andrew Butler (10 Jun 2020)

dino21 said:


> To provide minimal visual presence, mount it vertically though a hole in your main baffle, so just the face of the sensor is in the main tank


I'm a little unsure what you mean here, there is almost zero room between the rim and shut off level.


dino21 said:


> As you mention in your other post, a pair of wires/probes etc acting as a conductor will not be practicalbe/ reliable


I'm unsure where I've said this, maybe I got confused and wrote it by mistake but still see using the water to complete a circuit as the most efficient method if I can work it out and source parts easily.


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## dino21 (13 Jun 2020)

Hi,

Just a footnote  - our TDS probe has finally arrived, its just the bare probe and ciruit board,  not like a complete HM pocket meter.

As you can see even with its very small pair of metal probes its still as big as the opto and probably looks as obvious.

While the probe(unclaibrated) was quiet accurate,  due to the distance between the two metal probes it holds some  water between them after its been lifted out of the tank, , and so senses a reading,   if used as an oveflow preventer it might take some time before it senses 00 again and switches your pump etc back on.


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## Andrew Butler (17 Jun 2020)

dino21 said:


> As you can see even with its very small pair of metal probes its still as big as the opto and probably looks as obvious.
> 
> While the probe(unclaibrated) was quiet accurate, due to the distance between the two metal probes it holds some water between them after its been lifted out of the tank, , and so senses a reading, if used as an oveflow preventer it might take some time before it senses 00 again and switches your pump etc back on.


I wouldn't need them to be so close, one could remain submerged at all times (if I chose).

IF I decided to go this route and it works I could drill a small hole through the acrylic below water level for one part and the other could be discreetly 'hung over the edge'

Undecided which option to persue.


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## dino21 (17 Jun 2020)

Just something that might be of interest to others well as yourself.

Had chance to test out this level sensor, to give an idea of scale, its a 2 ltr container, the sensor is 28mm in diameter and it has a red led to indicate hi or low, as well as an output for other control.

The difference seems to be just 1-2 mm  both ways, taking 25ml of water to effect a change, so really quiet accurate.  Test repeated several times, but no idea if  different  thicknesses  of glass has any effect  on this level?

The top of the sensor  above the level sensing point is about 13-14mm, so with your running 10mm level and I would suspect an overflow  level of  5 mm (?)  so the  sensor would project about 8-9 mm above the glass.


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## Andrew Butler (24 Jun 2020)

dino21 said:


> As you mention in your other post, a pair of wires/probes etc acting as a conductor will not be practicalbe/ reliable imho


It seems Innovative Marine disagree and is the method they choose for their 'HydroFill ATO' - maybe a method I've given up on (or thought I had) but found this by mistake.





https://www.innovative-marine.com/shop/HydroFill™-Ti-ATO-Controller-p184824859
https://www.innovative-marine.com/shop/Parts-HydroFill™-Ti-Replacement-Controller-Sensor-p185023950


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## dino21 (25 Jun 2020)

With so many folk reliably using the float switches , opto  and contact sensors,  think its unlikely you will find much info on the metal probe sensors for aquarium.
You will have to try it out for yourself, after finding a suitable circuit, ac or dc, to control things, though making  something  yourself thats not well proven would not seem the best approach for an emergency device ?


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## Andrew Butler (25 Jun 2020)

dino21 said:


> With so many folk reliably using the float switches , opto  and contact sensors,  think its unlikely you will find much info on the metal probe sensors for aquarium.
> You will have to try it out for yourself, after finding a suitable circuit, ac or dc, to control things, though making  something  yourself thats not well proven would not seem the best approach for an emergency device ?


You do /did hear of disaster's using optical devices not so long ago, however I've been using them for ATO sensors in several aquariums for a while now and so far, so good.

Finding an optical device that is smaller in size including mounting is the challenge with regards to infrared, AutoAqua make them and route I've looked into and all being well will work out how I'd like.

Capacitive sensors from information I'm given needs being held secure to the glass and gluing is recommended I'm told. Also would be unable to have the sensor in my filtration partition as there is water in there also. This is all just information given to me by retailers/manufacturers.

I completely agree using something that's not well proven wouldn't be a good idea and would of course be tested before, regardless of the method I choose.


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## jaypeecee (25 Jun 2020)

Hi @Andrew Butler 

The photo shown in post #20 uses a vertical float switch just like the one I have in my main tank (out of action pending a revamp). It's based on tried-and-tested reed switch technology. When I first started using this, I was concerned that it would stick out like a sore thumb because it was white. But, after a couple of months, trusty biofilm has changed all this. I also haven't found it necessary to have a guard around it but, if large/heavy fish were to land on it, this could switch it from ON to OFF or vice versa.

If you're still hesitant about the capacitive sensor re gluing it to the tank, could you not clamp it to the glass or use a magnet perhaps? Neodymium magnets come to mind but they are very powerful and I haven't yet mastered working with them. Handle with care!

JPC


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## Andrew Butler (26 Jun 2020)

jaypeecee said:


> If you're still hesitant about the capacitive sensor re gluing it to the tank, could you not clamp it to the glass or use a magnet perhaps? Neodymium magnets come to mind but they are very powerful and I haven't yet mastered working with them. Handle with care!


It's the position it would need to be in, at the back of the clear glass I look through in the main display and would stick above, something I'd rather avoid if possible. As for mounting them I know something is being worked on by someone, exactly what I'm unsure.
Yes, I've shattered a few when trying to gently put them together; have you ever tried any kind of rubberised coating?

I think I have something sorted that will be a compromise and if it doesn't work/look how I want then can be changed easily.
I do still wonder about my original idea and the simplicity of the method, can always try it and see how it goes alongside.


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## jaypeecee (26 Jun 2020)

Andrew Butler said:


> Yes, I've shattered a few when trying to gently put them together; have you ever tried any kind of rubberised coating?



No, I haven't tried the rubberized coating but thanks for the suggestion.

JPC


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## Andrew Butler (26 Jun 2020)

jaypeecee said:


> No, I haven't tried the rubberized coating but thanks for the suggestion.
> 
> JPC


I've not yet either but it's on my planned to do list, if you get there first, let me know how you get on.


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