What's bad about water from water changes?

[jjencek]

I do 15% water change every two weeks. My tank is a SPS tank. I export nitrate and phosphate via skimmer and refugium and GFO. The nitrate is 5 ppm and Phosphate is 0.025. I dose Ca, Mg, Kh, and Red Sea colors and Red Sea nutrition.

I throw the 15% away (40 liters). What's bad about it?

I am now starting a breeding tank with a pair of clowns, pair of cardinals, and pair of peppermint shrimp. I plan to do water changes every two weeks.

Now the question is ... Can/should I used the water from my SPS tank?

[mcgyvr]

Assuming you don't collect it by sticking the tube into the sand where the water will come out brown,etc... then nothing is really bad about it.. Its the exact same water that was in your SPS tank (just seconds before the water change)..

If the water in the breeding tank is higher in nutrients then it would be beneficial to use.. Not as beneficial as brand new water with 0 nitrates/phosphates though..

[bertoni]

It's probably good enough, but it will likely have more nutrients and more ionic shift than fresh water, depending on what's going into the SPS tank, etc. A breeding tank likely will be fine with it.

[jjencek]

Originally Posted by bertoni

It's probably good enough, but it will likely have more nutrients and more ionic shift than fresh water, depending on what's going into the SPS tank, etc. A breeding tank likely will be fine with it.

I don't know much about ionic shift. I tried to read up on it, but still not clear. If I understand it at all - it is a build up of chloride when using Calcium Chloride for maintaining calcium levels in my DT.

The 170 liter breeding tank will have some live rock, sand, 4 fish, 3 shrimp, and a cleaning crew. I might also throw in a few corals for decoration and maybe an anemone for the clowns. Because the breeding tank will have very little corals, I don't expect adding much Calcium chloride.

One more question I have is if I should use all of the water from my larger 350 liter tank - making it close to 30% water change for the breeder. I feel like that is too much.

[ThRoewer]

I always used water from the parents tanks for the larva with very good results.
For raising post metamorphosis juveniles water from a coral system should be more than fine. There is really no reason to toss it and use freshly mixed water instead. If you ever get to the numbers of clownfish babies I raised you will see that there is really no point in wasting perfectly good water as 400 to 600 juvenile clownfish will poop up freshly mixed water just as quickly. I had to do 90% water changes on a weekly basis at the grow out tanks and rather routed those water changes through the broodstock and display systems than doubling my water consumption by using new water for those little poop factories.

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[bertoni]

Originally Posted by jjencek

I don't know much about ionic shift. I tried to read up on it, but still not clear. If I understand it at all - it is a build up of chloride when using Calcium Chloride for maintaining calcium levels in my DT.

That's one example of ionic shift. Any time we add something to the tank, we are adding some ions that stay in the water column. For something like Kalk, that's just some small level of impurities. For other supplements, like trace elements, there are more changes involved. We don't know for sure, but some tanks that seem to have problems without water changes might be suffering from gradual shifts in the chemical (ionic) content of the saltwater in them. So I recommend doing a 10% change once a month, or more, as needed for other reasons.

I probably would limit the changes to 10-15% unless there's some emergency, but larger changes can be safe, although they are a bit more risky.

I always used water from the parents tanks for the larva with very good results.

I agree that that sounds like a fine use of water from changes. I would be more concerned with a tank that contained a lot of touchy corals.