looking for a simple top off idea

[skyhawk8519]

iv heard of people using really simple methods for their top off system. One involving just a 2 litre bottle of RO water and placed above the tank, connected to a float switch so it fills up when needed


anyone know how this is put together?

 

[mr pink floyd]

i just pour in a gallon or so every 2 days

 

[dogstar74]

Glass vessles work better. they don't flex as much. I will try and draw up a diagram and see if I can scan it in.

 

[dogstar74]

Here try this one.

 

[mermin]

im definitly gonna try that but could you explain it more. like where t place the two tubes i know one is allways under water but what about the other one

 

[AIMFish]

Lol, that's the idea I tried to explain the other day Patrick, except I was planning on a 20oz./2l. bottle and both lines in the tank being equal.

 

[scubaD]

very inventive sollution. It is an air pressure thing. When both tubea in the aquarium are under water, water being siphoned from the bottle creates a vacuum in the bottle which stops the water flow. When the water in the tank drops below the shorter hose, air floods into the bottle equalizing the air pressure in the bottle releasing the siphon to fill the tank more. Very cool. I might have to try that.

 

[Phyto]

I hang a full 3 liter soda jug, upsidedown in the sump. Just leave the opening of the jug where you want the water level. When the water level goes down, water comes out. It stops when the water level reaches the mouth of the upsidedown jug. It's the same basic principal as dogstar74's, just with out the airline.

 

[chocolateblnt]

Look in the Nano Forums DIY sticky thread ...

 

[dogstar74]

Thanks for everyone else explaining the principles behind the drawing. Pretty simple really. But I do think a glass bottle would be better than a plastic one, just because you'd have a shut off delay as the bottle flexed, and also, those 2L bottles can make some nasty popping sounds when they flex. But to each their own. I really like the turn the bottle upside down thing! That rocks. It's kinda like those multi-day cat watering cans huh? Good idea!

 

[mfp4073]

I messed with this using a semi ridgid plastic water bottle (much stiffer than a 2 liter bottle) and still had some problems with it. I started using a "metered drip" setup. Basically the same thing, but instead of the second line I used a valve to set a drip equal to evaporation. Worked pretty good, but my valve was not "fine" enough to get set just right. I have some hospital style "drip meters" (the kind on IV bottles) on order and am going to try that next.

 

[sundevil_brian]

<a href=showthread.php?s=&postid=7872086#post7872086 target=_blank>Originally posted</a> by Phyto
I hang a full 3 liter soda jug, upsidedown in the sump. Just leave the opening of the jug where you want the water level. When the water level goes down, water comes out. It stops when the water level reaches the mouth of the upsidedown jug. It's the same basic principal as dogstar74's, just with out the airline.

The prob i see with this set up is that the fresh water in the top-off is going to difuse into the salt water causing the sinity to drop and then rais up again when the water alevaporates. this fluctuation in salinity might adversly effect corals and fish depending on the ratio of fresh water added to salt water in the system.

but if you haven't noticed any adverse effects then this is a great set up.

 

[skyhawk8519]

<a href=showthread.php?s=&postid=7885361#post7885361 target=_blank>Originally posted</a> by sundevil_brian
The prob i see with this set up is that the fresh water in the top-off is going to difuse into the salt water causing the sinity to drop and then rais up again when the water alevaporates. this fluctuation in salinity might adversly effect corals and fish depending on the ratio of fresh water added to salt water in the system.

but if you haven't noticed any adverse effects then this is a great set up.

well, the whole idea of "top off" water is to replace the "100% pure" h2o (fresh water) that evaporated. An automatic top off system allows water to be replaced as it evaporates, thus eliminating the fluctuation of salinity.

 

[traveller7]

The issue sundevil describes is the movement of freshwater into the tank and the movement of saltwater into the freshwater top off vessel through diffusion when top off is not supposed to be occurring.

They are always connected via a submerged tube; so salt will constantly attempt to diffuse into the top off bottle through the hose in the same manner the salinity within the tank itself reaches equilibrium. It may take time to occur through a smaller interface, but occur it will. The only question is the rate of diffusion problematic? The answer to that relates to diameter of tube, evaporation rates, size of vessels, etc.

Will this design work for some, yes, but it may not achieve an aim of "set and forget" for a week at a time.

 

[sundevil_brian]

<a href=showthread.php?s=&postid=7887873#post7887873 target=_blank>Originally posted</a> by traveller7
The issue sundevil describes is the movement of freshwater into the tank and the movement of saltwater into the freshwater top off vessel through diffusion when top off is not supposed to be occurring.

They are always connected via a submerged tube; so salt will constantly attempt to diffuse into the top off bottle through the hose in the same manner the salinity within the tank itself reaches equilibrium. It may take time to occur through a smaller interface, but occur it will. The only question is the rate of diffusion problematic? The answer to that relates to diameter of tube, evaporation rates, size of vessels, etc.

Will this design work for some, yes, but it may not achieve an aim of "set and forget" for a week at a time.

yea this is exactly what i was trying to say, thanks for putting is so eloquently traveller7

and i meant to say the sw would difuse into the fresh not the other way around

 

[dogstar74]

Actually, if you incorporate an IV bubble trap in the return line, then there is no way they can diffuse across it since it has a bubble in it. Sounds pretty much like set and forget to me!

Sweet.