auto water change...

[DrewPalmer04]

Negative air pressure creates suction. So that's why I'm curious what he means. Also mixing old with fresh would mean it wouldn't be 100% clean water? I guess I'm confused

[dazza1304]

We are talking about displacement of air right? AKA suction? The idea is great! I would however use two tubs connected via a air tight line..this would allow the suction to build in the second (dirty water collection) tub while pumping 100% fresh salt water out of the other...the dirty water collection tub could then also have a ball-valve for emptying the dirty water to whereever you would like it to go...

same concept..just a little tweek to not allow dirty water to cycle with fresh.

Hi, no offence, but this definitely will not work.

Reason is that you will end up with a different volume removed than added because of the ability to compress/expand air readily i.e. water change water will be added to your tank for a while without liquid been drawn out until such time as a sufficient vacuum is formed - so more water will be added than removed.

For example - if you take a bicycle pump, draw out the plunger and hold your finger over the end, you will easily be able to compress the air - because air is easily expanded or compressed. If you did the same and filled the pump with water, you would not be able to compress the water at all, because liquids cannot easily be expanded or compressed.

The model I mentioned has no air in the system (or very, very little) and thus what volume is dispensed is also withdrawn, maintaining the same water level.

Granted with the system I mentioned, if you are trying to achieve a 10% water change, what you actually achieve is a 9% water change. If the 10% or higher is critical of you, you just need a bigger vessel to accommodate a larger volume and then you will be able to achieve a 10% or greater water change in absolute terms.

Also, with my method, because of the mixing of the waste water with clean water, temperature differentials are minimised, and providing there is not too big a difference between the tank and water change temperatures, there is no need to heat the water change water.

Hope this makes some sense!!

[dazza1304]

We are talking about displacement of air right? AKA suction? The idea is great! I would however use two tubs connected via a air tight line..this would allow the suction to build in the second (dirty water collection) tub while pumping 100% fresh salt water out of the other...the dirty water collection tub could then also have a ball-valve for emptying the dirty water to whereever you would like it to go...

same concept..just a little tweek to not allow dirty water to cycle with fresh.

Hi, no offence, but this definitely will not work.

Reason is that you will end up with a different volume removed than added because of the ability to compress/expand air readily i.e. water change water will be added to your tank for a while without liquid been drawn out until such time as a sufficient vacuum is formed - so more water will be added than removed.

For example - if you take a bicycle pump, draw out the plunger and hold your finger over the end, you will easily be able to compress the air - because air is easily expanded or compressed. If you did the same and filled the pump with water, you would not be able to compress the water at all, because liquids cannot easily be expanded or compressed.

The model I mentioned has no air in the system (or very, very little) and thus what volume is dispensed is also withdrawn, maintaining the same water level.

Granted with the system I mentioned, if you are trying to achieve a 10% water change, what you actually achieve is a 9% water change. If the 10% or higher is critical to you, you just need a bigger vessel to accommodate a larger volume and then you will be able to achieve a 10% or greater water change in absolute terms.

Also, with my method, because of the mixing of the waste water with clean water, temperature differentials are minimised, and providing there is not too big a difference between the tank and water change temperatures, there is no need to heat the water change water.

Hope this makes some sense!!

[joshsbk]

i think i know an alternative way, correct me if i am wrong. why not use the double dosing pump. put one pump set up to suck from the aquarium and one to suck from a saltwater jug. the dossers are very reliable and could be set up with a timer to set how many gallons to change out per day using the .75ml/sec flow rate. just set it up so it removes 2 gallons while the ATO is off and then add it right after time settings for that would be for example:

ATO off @ 1am
Pump 1 (remover) on @ 1:30am off @ 4:30am (2gallons)
Pump 2 (replenish) on @ 5am off @ 8am (2 gallons)


I think I would only do it with a salinity probe to make sure you maintain a tight salinity reading. I would also use two water sensors one in the waste water tank to keep from accidental overflow as well as one at the top of your sump for the same reason. to me this would be the safest way to do a automatic water change.

I may be a little over worried but I am a koi pond professional and i have literally seen tens of thousands of dollars in dead fish from a faulty piece of equipment from a automated water changer. nothings will ruin your day more! so think this stuff out well before you do it!!

[DrewPalmer04]

So any code for the original poster's idea?

[dazza1304]

I think auto water change just got a lot more easy with the new water level sensor!!

[alexwbush]

Did you get one? I am away from home for work, but will be working on it when I get back. Only thing I debate about is whether to go the wet skim route or pump out.