Water Evaporation

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PAZE

New member
How much water evaporates in lets say a 100 gallon tank in a day?
When water evaporates, from my understanding the salt is left in the tank, and only water goes now would the salinity levels change as the water evaporates? would they be higher because water is less and the salt is more, does this make since? The reason I ask if you don't have ATO, and your topping off every 3-4 days is there a possible effect on corals/fish for higher salt levels?.
 
How much water evaporates has a million variables. So let's not focus on that.

Yes only water evaporates leaving the salt behind. As the water evaporates the salinity will increase. As long as your keeping reasonable amounts of water in there it will be fine. Might I suggest setting a full mark. Take a salinity reading at that mark. Then let your tank evaporate 1/2 inch, what's the reading now? If you feel its a safe level you could let it go more or just place a mark there. This will allow you to set a safe low water level. Please keep in mind water level needed for filters/overflows etc.

So now you have a fill to mark and an add mark......

Overall I suggest an ATO, this will allow for consistency which is really what fish/corals need.

Make sense?
 
Yes to all those questions. Most folks lose 1-4% daily, and topping off each day is often needed. I think an ATO is the best plan, and you can use limewater (kalkwasser) in the ATO.
 
As already stated, a lot of variables.

Personally, my 65G tank evaporates a little over half a gallon a day. I don't have an ato, I just keep a bucket by the tank and top it up ever 1-2 days. I have a sump, so the level in the display does not change. I have a max and min line drawn on the return section of my sump. With my evaporation, my fish and corals don't mind the minor change in salinity.

where in Ontario you from?
 
It's a good idea to make a habit of topping off your tank with fresh RO/DI water every day. It only takes a moment or two and it keeps the salinity level more consistent. Why expose your livestock to continual changes over a three day period when it isn't necessary?
 
@PAZE

I evaporate almost 10g every week in my 75g dt with sump......I use a tunze osmo and love it.....I'm getting an apex soon and am hoping it can fulfill my ato needs as well as my tunze does......the thing I love about the tunze osmo is that water only has to drop not even 1L and the sensor will top it up......hoping the floats I will have to use with apex are close to as accurate and stable. I am also curious where u are in Ontario?
 
OK so this leads me to my other question, if your getting ten gallons evaporation a week on a 75g, are you still doing weekly/monthly water changes? almost seems pointless when your pretty much adding more then 50% freshwater monthly.

kookie guy I'm in Burlington
 
PAZE said:
OK so this leads me to my other question, if your getting ten gallons evaporation a week on a 75g, are you still doing weekly/monthly water changes? almost seems pointless when your pretty much adding more then 50% freshwater monthly.

kookie guy I'm in Burlington
Click to expand...

Water changes are used to remove things that build up and replace things that have become depleted relative to the new water.

Replacing evaporated water with pure fresh water does neither of these things at all, so it has no bearing on the utility of water changes. :)
 
Yeah, unfortunately like salt, nitrates, phosphates, and other built up chemicals do not evaporate. Just water. In fact, that's the principle behind distilling water or alcohol. The water evaporates but leaves all the contaminates behind. Or in brewing, the alcohol boils off at a lower temperature than water, so it makes the drink have a higher proof after it condenses.
 
Thanks guys this makes things allot clearer.
Always wondered if it was possible to have a constant drip of freshwater going in and constant drip of bad water draining out would work? or would it soon just eliminate all good in water over a period of time?
 
It's actually more effective to do larger water changes than many small ones, which is essentially what a constant drip would be. Think of it this way, you want to change out 10 gallons of water.

Option 1 is to remove 10 gallons of water and dump 10 back in.
Option 2 is to remove 5 gal, add back 5 gal, remove 5 more gal, and add back 5 gal.

In option 2, you are actually removing a small portion of the clean water that you just added. This effect would be magnified a lot more with a constant drip.
 
Nice to still see you dpping these forums Randy. My question is if keeping the salinty at 1027 is still the best option or is lower better?
 
jrp1588 said:
It's actually more effective to do larger water changes than many small ones, which is essentially what a constant drip would be. Think of it this way, you want to change out 10 gallons of water.

Option 1 is to remove 10 gallons of water and dump 10 back in.
Option 2 is to remove 5 gal, add back 5 gal, remove 5 more gal, and add back 5 gal.

In option 2, you are actually removing a small portion of the clean water that you just added. This effect would be magnified a lot more with a constant drip.
Click to expand...

Well, that is true, but it is not nearly that extreme. One 10% water change is equivalent to 10.52% changed continuously. The difference is really very small and continuous water changes are a very good way to go.

I discuss the math here:

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

But simplistically, suppose you break that 10% water change down into one 10% change, or 100 x 0.01% changes.

By your comment, you'd think that the 10% change is a lot better, but it is not, it changes 10% .

The 100 changes of 0.01% results in an effective change out (0.999)^100 --> 9.52%.

That difference of 10% vs effective 9.5% seems pretty small to me. :)
 
I guess I won't question the math of a chemist, and you've obviously put more thought into it than I have. It doesn't feel right though. haha
 
I do my water changes with a tunze osmolater and just scoop water out of the top of the display tank and then the osmo replaces it .....I do this slowly......I change out 10 gallons of water every week too.....I change 5 gallons at a time over a period of 2 - 3 hours.....have had good success so far.....I am wanting to automate my water changes in the future and I was thinking of doing something like 1.5 gallons every day.....any thoughts?
 
I have 35g total and loose about 7g a week. My ato turns on at least every 2 hrs when the lights are on. I have an open top tough...
 
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