Exposing corals / coraline algae to air during water changes. Am I doing something bad?

[Kongar]

Let’s start with a quick story about coraline algae, an observation, and then my question.

First, I’m happy to report some great growth recently, corals and coraline algae. Interestingly, I noticed a sharp horizontal line where coraline algae would not grow above this line. At first I though this was related to the angle of my lights - maybe my lid creating a shadow. But the angles didn’t line up, and why was it so straight and horizontal? Something didn’t add up.

Then yesterday, I did a larger water change. Exactly twice the normal amount. When I was done (about 30min later), I noticed a horizontal band of coraline algae at the top that had turned bright pink. Then it all magically clicked for me.

The coraline algae won’t grow above the water line during my regular water changes, and when I did a double amount water change, a band of equal sized clearly showed stressed pink coraline algae. I’m assuming this is from the air exposure, maybe a temp drop as a result of being out of the water.

Now the question. Is this normal? I can’t find a lot of topics on this, but I have googled a few with a similar experience. My concern is that I expose a few corals to air during water changes as well. Am I inadvertently hurting them, and should I change my water change practices? If it’s bad enough for the coraline algae, it can’t be good for the corals...

 

[Sharkbait19]

The corals can be out of the water for a bit just like any aquatic organism, just try to minimize that time. Certain types can stay out longer than others.
As for the coralline algae, I noticed a similar line in my tank, right where the water change level is.

 

[NeonRabbit221B]

I think its a matter of exposure over time. if your water changes take 3 hours because you are using airline tubing to siphon and a solo cup to replace the issue it will be dramatically worse compared to doing the water change from your sump and the corals never being exposed.

I wouldn't expect that under normal circumstances for this to be an issue. Another suggestion is to avoid pumping or dumping the new salt water over the corals themselves. How long does it normally take you?

 

[T-J]

Corals release a slime coating when exposed to air. I think you're fine. Many reefs get exposed to sunlight for hours every day during low tide.

 

[Tundra Cuttle]

This will not hurt your corals, depending on the length of time they are exposed, is it a normal practice for you? Coralline algae for me has been very finicky and hardly grows if at all, I don't think it is air exposure that would just kill it. What sort of light intensity do you run? It might kill it if it dries out completely before getting back under water.

 

[Alexopora]

Let’s start with a quick story about coraline algae, an observation, and then my question.

First, I’m happy to report some great growth recently, corals and coraline algae. Interestingly, I noticed a sharp horizontal line where coraline algae would not grow above this line. At first I though this was related to the angle of my lights - maybe my lid creating a shadow. But the angles didn’t line up, and why was it so straight and horizontal? Something didn’t add up.

Then yesterday, I did a larger water change. Exactly twice the normal amount. When I was done (about 30min later), I noticed a horizontal band of coraline algae at the top that had turned bright pink. Then it all magically clicked for me.

The coraline algae won’t grow above the water line during my regular water changes, and when I did a double amount water change, a band of equal sized clearly showed stressed pink coraline algae. I’m assuming this is from the air exposure, maybe a temp drop as a result of being out of the water.

Now the question. Is this normal? I can’t find a lot of topics on this, but I have googled a few with a similar experience. My concern is that I expose a few corals to air during water changes as well. Am I inadvertently hurting them, and should I change my water change practices? If it’s bad enough for the coraline algae, it can’t be good for the corals...

I can’t remember which thread but a fellow reefer asked a similar question a few months back. They had coralline that would not grow beyond a certain level. As for me, generally only my sps and corallines get exposed to the air during water changes since they are located in upper sections of the tank. They normally don’t spend longer than 20 minutes in the air during water changes. Hmm, it could be a combination of the exposure to air, a change in temperature (esp if you are either using a chiller or a heater), and the increased exposure to the lights (due to the absence of water since light is diffused by water).

 

[Alexopora]

Corals release a slime coating when exposed to air. I think you're fine. Many reefs get exposed to sunlight for hours every day during low tide.

Do correct me if I’m wrong but not all corals get exposed to the air and direct sunlight in the wild. I believe most reefers don’t just keep shallow reef corals in their tank.

 

[T-J]

Do correct me if I’m wrong but not all corals get exposed to the air and direct sunlight in the wild. I believe most reefers don’t just keep shallow reef corals in their tank.

No, not all corals are exposed to the air. However, they will release a slime coating (ever notice when you're adding frags to a tank?) for protection.
Just saying that generally speaking, if your coral is exposed for a short time, it'll be fine. Before they arrived in your tank, they were taken out of the water, cut up on a saw (or bone cutter), and glued to a plug before being places back into the water.

 

[Tundra Cuttle]

Corals are adaptable and if it is a normal practice they will be fine especially if it is not a long time

 

[Alexopora]

No, not all corals are exposed to the air. However, they will release a slime coating (ever notice when you're adding frags to a tank?) for protection.
Just saying that generally speaking, if your coral is exposed for a short time, it'll be fine. Before they arrived in your tank, they were taken out of the water, cut up on a saw (or bone cutter), and glued to a plug before being places back into the water.

Oh tell me about it, especially when you have a plating monti (about the size of my palm). It will just drip slime all over.

 

[Kongar]

So I did find that one thread where someone had a very similar experience, but there wasn't any answers, nor was there any questions addressing corals. My corals don't seem to care one bit. After a water change, they look their best. I've also seen countless videos, and read numerous stories of people doing water changes and exposing corals to air, and this seems normal.

Being a noob only 1 year into the hobby, I've made my share of stupid mistakes. I was wondering if this was another one - but I didn't think so. Thanks for the confirmation. Weird behavior with the coraline algae in my tank though - yes? I'd bet the temperature drops significantly during a water change and that's causing the stress. My tank is in the basement, and it's generally pretty cold down there - about 65F. I don't hurry during water changes, so it's probably normal to be exposed to air for 20minutes or so once a week.

I guess this is just another way my tank likes to do non-normal things /shrug.

 

[Azedenkae]

Let’s start with a quick story about coraline algae, an observation, and then my question.

First, I’m happy to report some great growth recently, corals and coraline algae. Interestingly, I noticed a sharp horizontal line where coraline algae would not grow above this line. At first I though this was related to the angle of my lights - maybe my lid creating a shadow. But the angles didn’t line up, and why was it so straight and horizontal? Something didn’t add up.

Then yesterday, I did a larger water change. Exactly twice the normal amount. When I was done (about 30min later), I noticed a horizontal band of coraline algae at the top that had turned bright pink. Then it all magically clicked for me.

The coraline algae won’t grow above the water line during my regular water changes, and when I did a double amount water change, a band of equal sized clearly showed stressed pink coraline algae. I’m assuming this is from the air exposure, maybe a temp drop as a result of being out of the water.

Now the question. Is this normal? I can’t find a lot of topics on this, but I have googled a few with a similar experience. My concern is that I expose a few corals to air during water changes as well. Am I inadvertently hurting them, and should I change my water change practices? If it’s bad enough for the coraline algae, it can’t be good for the corals...

Different coralline species react differently to dessication, but yes could be a factor: https://onlinelibrary.wiley.com/doi/abs/10.1111/jpy.12161

 

[Kongar]

Actually, I just realized I have a visual of it. if you go to my build thread and watch the latest video I posted the other day, right at the beginning, you can 100% see the sharp horizontal line on the black back that coincides with my regular water change line. About 3/4 through the vid you get an even better shot of it. Yesterday, I dropped the water level about 4 more inches lower than that line, and all the top algae turned neon brightest pink that's ever been pink. The lights haven't come back on yet today so I don't know if it turned regular colors or not yet.

Anyways, there's alway something interesting going on in my tank - part of the fun of the hobby!

 

[Kongar]

How long does it normally take you?

20 minutes and I'm usually done. Most times, they are exposed for about 10 minutes while I drain and then fill with another bucket. I generally change the water, then futz with equipment (like changing carbon, filters, etc.)

 

[Kongar]

What sort of light intensity do you run?

At that spot - it's about 250 PAR. Maybe a little less because of the angle.

 

[Kongar]

As for the coralline algae, I noticed a similar line in my tank, right where the water change level is.

Always helpful to hear when you're not alone Thank you

 

[Tundra Cuttle]

At that spot - it's about 250 PAR. Maybe a little less because of the angle.

Maybe my lights aren't strong enough to grow coralline algae? Maybe my macroalgae competes with it too hard, no clue, I do have some red Coraline that hasn't died.

 

[Sharkbait19]

Here’s how it looks for me:

As you can see, it becomes a brighter pink at the line where I do water changes, then stops growing. It seems that somehow, the short amount of time that area is exposed to air is enough to prevent coralline growth.

 

[Kongar]

Maybe my lights aren't strong enough to grow coralline algae?

I'd guess your lights are probably fine.

My coraline algae started about 4 months in - little itty bitty spots here and there on the rocks. Nothing on the glass. But it never really grew much - just dots. Then I battled dinos for what seemed like forever, and frankly nothing was growing well during that time. But then it just exploded, starting sometime around the beginning of april. It's growing in spots that are only about 100 PAR. Now it seems to grow everywhere - EXCEPT, above the water change line, on the glass.

 

[Kongar]

Here’s how it looks for me:

As you can see, it becomes a brighter pink at the line where I do water changes, then stops growing. It seems that somehow, the short amount of time that area is exposed to air is enough to prevent coralline growth.

Cool! Well I guess that confirms it then - it's just a thing... Guess some coraline algae just isn't as hardy as corals themselves.