adding fresh water instead of salt

[LA ICK WARRIOR]

is it possible to only add fresh rodi water to my salt water tank since salt doesn't evaporate? or are there certain parts of salt that need to be replenished. reef vs fish only? I literally have only added fresh water to my sump when it gets low from evaporation and haven't taken any water out for at least 2 month. I have 1 coral, an ocelaris clown, diamond goby, and fire shrimp. don't know the coral name but it looks like a circle shaped tongue with dandelion like tentacles that come out with light.(any guesses?) it has gotten smaller/ deteriorated, and tentacles dont come out as much

20 gallon tank, 20 gal sump, and ebay skimmer.

[vhuang168]

You should only replenish any water lost through evaporation with rodi.

You should also do periodic water changes where you remove a % of the water from your tank and replace with fresh salt water. This will replace any trace that have been used up.


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[bertoni]

I agree that evaporation should be replaced with RO/DI water. For some tanks, the skimmer exports enough salt that some saltwater needs to go into the system from time to time.

[jayball]

Originally Posted by LA ICK WARRIOR

is it possible to only add fresh rodi water to my salt water tank since salt doesn't evaporate? or are there certain parts of salt that need to be replenished. reef vs fish only? I literally have only added fresh water to my sump when it gets low from evaporation and haven't taken any water out for at least 2 month. I have 1 coral, an ocelaris clown, diamond goby, and fire shrimp. don't know the coral name but it looks like a circle shaped tongue with dandelion like tentacles that come out with light.(any guesses?) it has gotten smaller/ deteriorated, and tentacles dont come out as much

20 gallon tank, 20 gal sump, and ebay skimmer.

RE your topoff question, the same as what the last 2 said.

For your coral question we need a picture to even get close. You just described half the coral in existance.

[reddtiger88]

Yes pure water only for top off. What is your setup like? Lights? Filter? Other information would be useful.

[sde1500]

Depending on how often you empty your skimmer, over time you may have to adjust salinity by topping off with a little saltwater. But you are correct otherwise, only top off with fresh.

[Martin Kuhn]

Evaporation
=========
is going on steadily as your water surface is moving and the heat brought in by your lighting takes up steam in the air of your room. result: water is evaporating, salt stays in your tank.
(the amount of salt that vanishes through a skimmer is in my eyes negligible)
this is happening day by day,the hotter and the more circulation, the more.
salinity is rising slowly

=> Adapt that by adding exactly the amount of sweetwater that vanishes!
the more often you do that, the better because your tanks salinity stays constant (=ATO)

if you tend to not use ATO salinity is going up each day but slowly. If you wait for a longer peiod of time and then refill all the lost water, this isn't a good idea. Salinity might drop too fast and generate a problem for some of your animals, especially shrimps.

Another side-effect of not having an ATO. Together with salinity rising.... also Ca/Alk and Mg levels go up artficially

Water changes
==========
There is a lot of good things happening , as long as you
a) take a "high quality salt mixture", where a lot of them are available
- having good ca,Alk and Mg levels (hint: look into the free light version of AquaCalculators salt calculator to find Ca/Alk/Mg levels of 75 available salt mixtures)
- correct amount and types of trace elements integrated)
AND
b) use RO water, no contaminated tap water


- you are "thinning" any impurities, toxines, nutrients (NO3, PO4)
- you are "adding" consumed trace elements. This is especially important as you can't measure it with normal test kits !)
- you are "correcting" a possible missalignment of trace elements (some trace elements are even toxic in too high concentrations)
- you do a "slight adjustement" and als "correcting" of the three major elements Ca/Alk/Mg (for tanks with LSP and SPS this might by far NOT be enough to adjust the comsumption!)
- Once removing salt water from your tank (before you add fresh salt water), you can remove gravel or other unwanted stuff from your tank together with it
- you can use a water change also for bringing down the "risen salinity" coming from a 2/3 part dosing

[reef thief]

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