# auto top off



## predator

ok guys im looking at doing a project and an auto top off for it isnt a must, but it would make things so much easier...

heres what im thinking... simple bottle hanging upside down with some airline through the cap... the line suction cupped to the side of the tank with its end at the level i want the water to stay at... it would basically be like an auto fill dog dish...










here is the problem... as a levler.... it would work great... cant think of a single issue it would have with over filling or anything... but... when topping off salt water you use freshwater... if you have a tube of freshwater touching SW the salt will leech up the tube lowering the SG of the tank... granted if you have a small bottle relative to tank size even if they truely match sgs the efect on the main tank wil be minimal... you cant put SW in the bottle or you will increase your sg as the water evaporates...

i guess im just gonna have to do an experiment and see how bad salt will leech up the tube... it might be slow enough not to even worry about it because of the downward flow when water refils the tank... 

anyone ever try this?... its sooo simple, but you never see it there has to be a reason you dont... and im guessing the salt mixing in your FW problem is y...

i have an idea to over come this that is a simple valve to keep the waters seperate that i will try if i have to... here is a simple sketch...










basically a hard plastic straw with holes cross drilled in it... a float ball is suspended in the tube... when levels drop the ball will lower and fresh water will exit through the holes in the tube... when the level of the water raises above the holes the ball will float up and block off the fresh water from the sw reducing leeching... the ball is not designed to stop the water flow... the holes will do that the ball is simply there as a divider between SW and FW... 

i dont know if it will work, but hey its all about trial and error...

-me


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## predator

hmm alot of input im gettin here... i had another brainfart... as we know i need a way to use no motors or anything to regulate water level without the chace of salt seepage into the fresh water.... the only way to do this is to not allow the waters to touch...

here is my idea... 










the theory behind it is when water levels drop the tube leading to the top of the bottle will drain and allow water air to enter the top of the bottle... this would allow water to drain from the bottom of the bottle... when the level gets to a point the shut off tube would begin picking up water and pull a vacuum on the bottle causing the water to stop draining from the tank refill tube...

-me


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## predator

nothing from anyone?... not even "ummmmm never gonna work"... am i too unclear on it or just asking the wrong ppl or what?

-me


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## fish_doc

From what I see it should work. I just dont have saltwater tanks so I have no experience with topping off a tank and dealing with the weight of freshwater vs saltwater. 

In basic understanding I would say saltwater would not go to far up the tube seeing how the actual physical weight of saltwater is heavier than freshwater.


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## SvenRhapsody

I would just get a cheap check valve at the hardware store. That should solve the problem. PVC is probably pretty resistant to salt water. I must say that from your description and sketch I don't see how this is working or why the bottle isn't just dumping it's contents into the tank, but I'm sure there is something there I'm missing.


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## predator

i too had thought about the check valve only problem with it its there has to be reverse flw up the tube... that is the only way air can get into the bottle and allow more water to exit...

and its the same basic concept as putting a cup under water and pulling it out upside down... it will hold the water until the seal around the lip is broken...

-me


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## mr.dark-saint

The IV chingus you're rigging with "auto" fill is too much since the float has to move up and down for it to work however water will just dump out and emptying the whole thing since it's not water tight (and working against downward pressure). I see the concept of the salt water pushing up the float to put pressure on the downward push of the fill water but will there be enough upward pressure to have a good seal? I could see a rubber gasket above the floaty ball but again will there be enough upward pressure (better seal yes but?). 

The whole thing reminds me of a "rodent" water bottle (you know the ones with two steel ball baring). 

Anyhow. The float has to be very (I mean extremely) buoyant to get a good seal. And the tollerances very tight or else it'll just empty out with out you wanting it to. 

As for it "leaching" I doubt it since Saltwater is denser than fresh water (think Jack Daniels floating on water or oil on top of water). 

And your last post. The cup holding water thing. It's a one shot deal since you'll have to calculate how much air comes in with the fill going out. Using gravity and vacuum will make a mess. Since they're hard to control.

A mechanical valve shut off would make worlds easier. Get one of those 1/4 turn valves (for air line valves in commercial pet stores). They're chrome finished brass with a lever turn (not the round knob type) ball valve. I could see one of these with a float that is heavier so when the water level drops the weight of the float will turn the valve in turn filling the sump. As the level goes up so does the float and in turn sutting the valve off. Think the old toilet float system (ones on long arms). Come to think of it if you can rig the newer toilet float valve in to your "system" it might make it easier. (you can skip my elaborate valve system for one on your toilet).


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## predator

dont think you quite get it... though i thank you for your attempt...



> The IV chingus you're rigging with "auto" fill is too much since the float has to move up and down for it to work however water will just dump out and emptying the whole thing since it's not water tight (and working against downward pressure). I see the concept of the salt water pushing up the float to put pressure on the downward push of the fill water but will there be enough upward pressure to have a good seal? I could see a rubber gasket above the floaty ball but again will there be enough upward pressure (better seal yes but?).
> 
> The whole thing reminds me of a "rodent" water bottle (you know the ones with two steel ball baring).
> 
> Anyhow. The float has to be very (I mean extremely) buoyant to get a good seal. And the tollerances very tight or else it'll just empty out with out you wanting it to.


the float isnt there to keep the FW in... the vacuum of the bottle will do that... it is simply to block off the majority of the contact area between the FW and SW reducing amount of salt transfer that will happen...



> As for it "leaching" I doubt it since Saltwater is denser than fresh water (think Jack Daniels floating on water or oil on top of water).


we arent talking oil and water here... if you shake oil and water... let it sit for a while you still have oil and water... if you shake FW and SW... over time you have... well a a volume of water equal to both parts added togethere with a salinity somewhere in the middle of what the two possessed prior to mixing... the salt will have a tendency to move from the area of higher concentration to the area of lower concentration... i just dont know if it will do it fast enought to ever really mix in the bottle (therfore lowering the sg of the tank)



> And your last post. The cup holding water thing. It's a one shot deal since you'll have to calculate how much air comes in with the fill going out. Using gravity and vacuum will make a mess. Since they're hard to control.


how is gravity and vacuum a bad idea... its used ever single day in pet drinking bowls every day... and ther is never a mess... 

i dont see how my second idea is a one shot deal... water cannot exit the bottle unless air (or some othere volume occupying material) is intering the bottle to take the place of the water... when the tube to the top is able to take in air that air will move to the top of the bottle and let out and amout of water... when the tube begins to draw water... the water column in the tube will pull a vacuum in the top of the bottle therefore shutting off the water exiting the bottle... (and it is impossible for water to get high enough to enter the bottle through the second tube... if this could happen you woudl have a perpetual machine...) and since water cannot be pulled high enough to replace the volume lost if fresh water exits the bottle and the water is blocking air from replacing the volume... you will form a vaccuum and the water will be held in...



> A mechanical valve shut off would make worlds easier. Get one of those 1/4 turn valves (for air line valves in commercial pet stores). They're chrome finished brass with a lever turn (not the round knob type) ball valve. I could see one of these with a float that is heavier so when the water level drops the weight of the float will turn the valve in turn filling the sump. As the level goes up so does the float and in turn sutting the valve off. Think the old toilet float system (ones on long arms). Come to think of it if you can rig the newer toilet float valve in to your "system" it might make it easier. (you can skip my elaborate valve system for one on your toilet).


umm yeah a toilet float in a 1 gal... prolly not gonna fit toooooo well... and i was looking at this from the point of veiw of someonew ith a small tank since both would only fill at slow rates anyway... (first one could be done big... second one the fill tube has to be small enough that the surface tention of the water will keep it from dripping...)

-me


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## AndrewH

The last drawing looks like it should work, but it's simple enough to test in the sink with an empty soda bottle and a straw.

If I get a change I'll try it out tonight/this weekend I'll let you know what I find.

(very nice idea btw)


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## fish_doc

Maybe a cheap toilet float would work. :evil: :evil: 

Sorry couldn't resist.

Actually I remember seeing somthing on the market that does this. I know this defeats the purpose of having a DIY section. But if I could remember where it was that I saw it someone could "reverse engineer" it and we could all benefit.


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## predator

ive been looking at nano tank stuff and havent seen one thats not electric or just based on dripping... non like this... and i just had a few minutes to brain fart on it...
-me


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## predator

im rigging it up right now....... ill let you know later if i can get he silicone dry tonight...

-me


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## fish_doc

Found one. A bit expensive.

http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=13959



also found this DIY model

http://avdil.gtri.gatech.edu/RCM/RCM/Aquarium/RefillSystem.html


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## predator

see all electric... i want to figure out something that isnt... that works...

-me

wish me luck im gonna lay around this weekend...


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## mr.dark-saint

predator said:


> dont think you quite get it... though i thank you for your attempt...
> 
> 
> the float isnt there to keep the FW in... the vacuum of the bottle will do that... it is simply to block off the majority of the contact area between the FW and SW reducing amount of salt transfer that will happen...
> 
> *If there's a vacuum in the bottle it'll suck up water from the fill tank. Beside how are you going to keep a vacuum in the bottle?*
> 
> 
> we arent talking oil and water here... if you shake oil and water... let it sit for a while you still have oil and water... if you shake FW and SW... over time you have... well a a volume of water equal to both parts added togethere with a salinity somewhere in the middle of what the two possessed prior to mixing... the salt will have a tendency to move from the area of higher concentration to the area of lower concentration... i just dont know if it will do it fast enought to ever really mix in the bottle (therfore lowering the sg of the tank)
> 
> *The "oil and water" analogy was used to show the separation (not the martini effect) since there is little chance where one'd do the shaken and not stired. I was working off the thought that you wanted to replace the evaporated water not a slow gravity defying osmosis. Might as well just make a Kalk water drip system.*
> 
> 
> how is gravity and vacuum a bad idea... its used ever single day in pet drinking bowls every day... and ther is never a mess...
> 
> *The cup and water thing. When the water level drops it's not a "smooth" transition (fill) it'll be more of a "Plop" action without an air going in to break the vacuum.*
> 
> 
> i dont see how my second idea is a one shot deal... water cannot exit the bottle unless air (or some othere volume occupying material) is intering the bottle to take the place of the water... when the tube to the top is able to take in air that air will move to the top of the bottle and let out and amout of water... when the tube begins to draw water... the water column in the tube will pull a vacuum in the top of the bottle therefore shutting off the water exiting the bottle... (and it is impossible for water to get high enough to enter the bottle through the second tube... if this could happen you woudl have a perpetual machine...) and since water cannot be pulled high enough to replace the volume lost if fresh water exits the bottle and the water is blocking air from replacing the volume... you will form a vaccuum and the water will be held in...
> 
> *This whole bit would work with a 2 liter bottle of fresh water inverted and placed in the container. If the 2 liter is too big then 1 liter (with a wide mouth)*
> 
> 
> umm yeah a toilet float in a 1 gal... prolly not gonna fit toooooo well... and i was looking at this from the point of veiw of someonew ith a small tank since both would only fill at slow rates anyway... (first one could be done big... second one the fill tube has to be small enough that the surface tention of the water will keep it from dripping...)
> 
> *This was just a thought since the valve system is prefab and less R/R.*
> 
> -me


If I knew of the size requirement my toilet valve system would not have made the post:lol: . It's alway fun to tinker.


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## predator

> If there's a vacuum in the bottle it'll suck up water from the fill tank. Beside how are you going to keep a vacuum in the bottle?


i guess vacuum is a bad word... well maybe not... and the vacuum will be formed by the weight of the water pulling down... and its more of a equalibrium then a vacuum i suppose...



> The "oil and water" analogy was used to show the separation (not the martini effect) since there is little chance where one'd do the shaken and not stired. I was working off the thought that you wanted to replace the evaporated water not a slow gravity defying osmosis. Might as well just make a Kalk water drip system.


i do want to replace the evaporated water... im trying to avoid the slow gravity defying osmosis, that is y i tried to seperate the SW from the FW in the second design... and y would i want a drip system that takes adjusting and might over flow when i have a fool proff system that will regulate the level no matter the rate of evaporation... even if i get it down to a few drops a minute that is alot in a 1 gallon...



> The cup and water thing. When the water level drops it's not a "smooth" transition (fill) it'll be more of a "Plop" action without an air going in to break the vacuum.


the plop all depends on how big of a tube you are running and you can always put an airline valve on it to adjust how fast the bottle empties...



> This whole bit would work with a 2 liter bottle of fresh water inverted and placed in the container. If the 2 liter is too big then 1 liter (with a wide mouth)


now that would cause a big ass plop... and a 2 liter stands the chance of collapsing on it self and causing an over flow... the best container to use would have stiff sturdy walls to keep the springing effect of the container to a minimum...



> If I knew of the size requirement my toilet valve system would not have made the post . It's alway fun to tinker.


i know i didnt list the tank size as a parameter not your fault...

oh by the way i tried the second one and couldnt get it to stop (got it to barely a trickle), but i had a small leak that im thinking caused this... (i know it had an effect) i did however pull water up the tube and get it to hold and "plug"... gonna reseal it tongit and try again... might ahve a working model as of saturday...

when testing i had a small enough hole that no bubbles were comming in through the the exit hole... sure it all had to do with my leak...

-me


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## AndrewH

Well I just thought about this too... What about a simple pin hole in the bottle's lid then another one in the top of the battle (with the bottle being upside down)?


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## predator

bottle would never stop drippin and unless the dripping was set up exatly perfect... you would prolly flood your tank...

-me


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## PetMax

bro i have one that is NOT electric. Ill post pics tomorrow. its a CoralLife autotopoff. its basically, a small plastic thing with a float valve on it. I have my tank on a wall, that seperates the kitchen/living room. I ran the water line to the ice maker line. 

Now, here may be the problem. Yes the water is cold, but with the autotop off only occuring in small amounts, and with my tank being a 220, that tiny amount of cold water doesnt make a difference. now for a smaller tank, i couldnt tell ya if it would make a difference or not.

Also, you may say that the water from the ice maker is not dechlorinated. But, in small amounts its ok as your water conditioner does not vanish from the tank. As being part of a pet store for over 7 years, i have NEVER put water conditioner in my tanks when i top them off every other day, and ive never had a problem. Most of the tanks at the store, at least the freshwater ones, are 20l/25l's. An my saltwater ones are all over 55g. Now, im not saying you can, nor do i say i recommend that, but thats what ive done without problems. When doing a _water change_, yes i do use conditioner.

Anyway back to the float valve, here is a basic drawing of what it looks like.


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## PetMax

oh, and if price is the problem, i think this thing was only like $15


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