storing old water for new tank

[rtbm]

I am upgrading to a lager tank roughly 180 gallons from a 90. I have been saving my water change water in preparation for this. I don't want to add that much new water when I transfer for a couple of reasons. One being that the alkalinity of my new water is considerably higher than what I keep my tank at. I don't want a spike like that if I can avoid it. Mostly I just don't like the idea of adding that much new water to my system. I may be wrong about this but it seems that doing so would be like doing a 50% water change. So like I said I have been saving as much water as I can in a 30 gallon container. I will probably have two by the time I change over. I put a small powerhead in there only. My question is, is there anything wrong with doing this, or any concerns I should know?

[Billybeau1]

Hmmmm. I think if it were my tank, I would not want to reuse any old water.

I would set up the new tank with 100 % fresh and let it cycle and do its thing. Then when all the important parameters match, transfer the fish and corals.

[Randy Holmes-Farley]

I too would use just the new water, but as long as the old water is well aerated all of the time, there should be no substantial problem using it.

How high is the alkalinity in the new water?

[rtbm]

I use Reef crystals it's around 11 give or take. I keep my tank at about 8.

[Randy Holmes-Farley]

A bump in alkalinity like that is not going to hurt anything, IMO. It will rapidly enough drop on its own once in the tank.

[rtbm]

so adding roughly 90 gallons of new water to 90 of old durring the transfer really is not a big deal? A while back I removed a few clams and a huge birdsnest at the same time I added a second stage to my reactor. My alk rose to around 12 very quickly and I did have some issues with a few acros. I should add they did subside after the alk dropped back down to 8 but since then I have been overly carefull when dealing with stability issues. Those are my real concerns.

[Randy Holmes-Farley]

No, not a big deal, IMO. A 50/50 mix would raise alkalinity to 9.5 dKH, and some folks have the alkalinity rise and fall that much every day if they are dosing a two part additive once a day. I don't think that is particularly stressful. The reactor situation may have been different in some way.

[rtbm]

ok you've convinced me. new water it is. Thanks again. I appreciate it

[Randy Holmes-Farley]

You're welcome.

Good luck. :)