Water Changes... Will Corals Dry Out?

[tangs_in_pacifica]

Probably a dumb question....
As I've now got corals and various sedintary inverts all over my system, my infrequent water changes are presenting a problem (I say infrequent because I'm so lazy that water changes are a rare event). Anyhow, If I try to do even a 15% change in the tank (after the sump has been emptied) I'm exposing corals to the air. That's because I've got LPSs all over the tank and SPSs that have actually grown until they're flat to match the surface of my tank. How long can I expose these guys, especially LPSs to air?
Again, even a 10-15% water change leaves all sorts of inverts out of the water. How does everybody else address this issue?

 

[green mariner]

No you should not expose them to air for any amount of time! You should be doing your water changes from the sump. If you cannot do it this way you need to find another way to do the water changes. Sorry to be the barer of bad news but it seems you don't have many options.
HTH

 

[tangs_in_pacifica]

Thanks, Mariner!
I was basically of the same opinion until recent power outages caused my to contemplate the relationship between corals and fresh air further. A few weeks ago, I was travelling on the East Coast, when my power was shut off for ~10-12 hrs! Yes, 10-12 hrs. (Long explanation). Anyhow, at that time I hadn't performed the return modification I've posted here. So, my water level dropped ~ 3-4" from it's normal level.
Now, the problem is that I have SPSs and some LPSs up to the very top of my tank. After over 10 hrs without water, I'm happy to report that my SPSs appear to have not lost a polyp. Unfortunately, my Anthelia has retreated somewhat, but is doing very well... considering the ciscumstances. There were a few other LPSs that were only partilly out of the water and they're unaffected. Anyhow, this event has caused me to ponder the relationship between corals and dry air. Anyhow, I'm really hoping that somebody can explain these observations? If they made it 10-12 hrs., can the make it for a 10-15 min. water change?
BTW - I've posted a quick modification that I performed to my returns so that my level will only drop 1 1/2-2" next time the power goes out.

[ June 11, 2001: Message edited by: tangs_in_pacifica ]

 

[burnnspy]

LPS and SPS corals can handle being out of the water for short periods of time.
I recommend agitating the LPS corals until they deflate, before draining the tank.
I also recommend having the change water ready to go so you minimize the exposure time.
The best course would be to put a valve in the sump supply line allowing you to stop the water flow so you can take water from the sump without draining the display tank.
BurnNSpy

 

[green mariner]

WOW 10-12 hrs. don't try this @ home kiddies!!
If this is the case you should be OK, but personally I try to keep my corals submerged at all times, IMHO it is un-needed stress. Unless of course, its fraggin' time!!

 

[coralbeauty]

I have a similar but worse problem. I have no sump. (Want one can't have it with my set-up.) So I do a BurnNSpy recommneds. I have 4 gallons of new water waiting as I take out the old. As soon as I am done, I start pouring the new water in slowly. It has not been a problem. I have SPS, xenia and gorgorian that get effected.
thanks,
Connie

 

[adrian]

You guys should check out some pics of the Great Barrier Reef at low tide I think it last anywhere from 3-5 hours and corals have a special mucus to protect them from UV. Of course most of the coral that are exposed to the air are sps.

 

[wolffam]

If you don't want to expose your corals during a water change try the following. Have your new water next to the tank with a pump returning the water directly to the tank. At the same time drain your old water into another bucket, must be able to hold an equal amount of water as the new water. By having a pump that replaces the water at the same rate at which you remove water, this keep the tank water level durin the water change, HTH.

 

[tangs_in_pacifica]

Wolf,
Thanks for the feedback. The method you described is how I currently change really large volumes of water. My fear in using this technique is that I'll wind up draining a significant percentage of the new water with the old stuff. IMOHO, getting the concentrated old stuff out is a top priority.
Adron, intteresting thought. Yes, it makes perfect sense that some of these corals are exposed at high tide. Hmmmm....?

 

[kodi]

In Vol 1 of The Reef Aquarium, Delbeek and Sprung, it is suggested to have your replacement water mixed and ready to go at about 5 degrees cooler than the tank temp. Pump the new water into the lower part of the tank as you pump water off the top of the tank. Because the cooler water is more dense than the existing tank water it will remain at the bottom until it warms and mixes. Should be plenty of time to do your water change without exposing your corals.

 

[burnnspy]

Since most tanks have pumps you cannot hope to reduce the concentration of waste if you add and remove water at the same time, reguardless of the temp.
Even without pumps running water changes create currents anyway.
Minimal exposure will probably only affect sponges and Goniporas, which won't usually survive capivity anyway.
BurnNSpy