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Discussion Starter · #1 ·
I need to do a 20% water change tonight. I just mixed the saltwater about an hour ago. I was always told that I need to wait 1 day after I mix it before doing the change. I really need to do a change now. I have a couple of xenia that do not look too good. I would like to do a bigger change but I only have enough water for 20% am I going to really hurt anything by doing it now?
 

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i just did a waterchange i let it mix probably for 30 mins tops in a 5 gallon bucket with a 750gph pump so i dont think it will "hurt anything" salt is salt but its better if its properly dissolved instead of chunks of salt in the tank or something (this is from my personal experience not liable)
 

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Newly mixed saltwater is caustic, it can burn the gills of your fish leaving them unable to breathe.

The 24 hour minimum mixing period is really necessary to allow the salt to fully mix in and stabilize.

Changing only 20% may not cause any problems but is it really worth the risk?
 

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Newly mixed saltwater is caustic, it can burn the gills of your fish leaving them unable to breathe.

The 24 hour minimum mixing period is really necessary to allow the salt to fully mix in and stabilize.

Changing only 20% may not cause any problems but is it really worth the risk?
+1

Do you have any fish stores close by that sell premixed water? Even PetCo carries it...
 

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Wow! 45 cents a gallon here.

What is 20% to you? To me it's 20 gallons. I use to mix it and add it. Never thinking. Never had ill effects either. But that was a 30 gallon display and did 5 gallons then. When I first set up my 90g I started keeping premixed in the garage with heater and pump.

Now I don't do water changes. Or at least I haven't since February after building an algae scrubber.
 

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Water changes serve two purposes. To replenish trace elements and to remove unwanted chemicals. Replenishing trace elements is easy and if it was the only reason for water changes, a tank could be run very successfully without doing them.

However, it is the removal of unwanted and untestable chemicals that is more difficult to accomplish. This goes beyond the usual nitrate, phosphate and other things that are easily processed by a biological filter or removed by a skimmer or refugium. Water changes are required to reduce the buildup of toxins within an aquarium that occur from natural (fish, corals, food, etc) and unnatural (airborne household chemicals, dust, dirty hands, etc) sources.

If you think you can have a longterm successful tank without ever doing water changes, you are fooling yourself.
 

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Discussion Starter · #10 ·
I did the water change, everybody seems happy right now. BUT, my nitrates are still 180+........man I can't wait to get my permanent tank set up and cycled!
 

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In 30+ years of keeping saltwater tanks and 25+ in reefs I have never let water sit for more than a few hours before using it. I do try to match the temperature, salinity and pH though, especially for large water changes.

Someone explain to me how it can be "caustic" ? Caustic would register on a pH meter would it not? Does something magically take place in the water? I don't buy into that myself. Todays salts are designed to mix with RO and RO/DI water and stabilize very quickly compared to salts of years gone by.
 

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Yeah, I fall on the side that it is better to wait 24 hours, but less time is ok in a pinch. Still, the trick is mixing completely. High volume pumps make it much easier to ensure that all of the salts mix completely and the more modern salt is better than old school salts. Still, the more it mixes the better. When salts are just being mixed, the alk/pH might not be stable... and high alkalinity/pH can be caustic as caustic refers to both strong acids and bases. The salt components are still finding an equilibrium because chemicals like to be balanced in a way. Still, as soon as you have a stable reading of pH, temp, Alk, salinity and such, the salt should be fine. There might be some issue with CO2/O2 for other reasons but I digress
 

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It's not a myth. It is very caustic newly mixed. A mixture that has a strong base can be caustic. You do see a PH swing (minor). PH is slightly higher when newly mixed and then stabilizes. It is about highly concentrated pockets of weak bases within the salt mixture (small bubble areas - difficult to test). It needs time to stabilize. It takes about 24hrs for full equilibrium to occur. Waiting a day or two longer will make sure the oxygen levels are adequate (if the water is being circulated).
 

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well, not a myth... just a rule where the therm "it depends" comes into play

24 hours is really a nice safe point for cautious hobbyist... and the rule came out of it. In small % changes, newly mixed SW would matter less, but big % change it is more important. Also, there is a lot of inconsistency when mixing 5g of NSW vs 50g of NSW. If it is a small batch, I think the 24 hour rule is more important. Kinda works on that level...
 
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