"tree line" effect to corraline?

[anewguy]

some time ago i posted this question and was told this was normal, but ive looked at a whole lot of tanks before and since, and it seems corraline always grows evenly across the back of tanks. mine stops and there is no growth all the way across the back in nearly a straight line. it is growing on a powerhead thats higher in the tank that sits closer to the front glass though. all params are good and tank has been stable for some time. lights were changed in september, though this has been like this before then. im just really curious about this and was wondering if anybody had any ideas. thanks much.

 

[Reefmack]

That is strange. Maybe related to the light from the hood not being as intense on the upper back wall? I'd guess the coralline will move up there eventually.

 

[soily]

Snap, i have exactly the same in my tank (although mines a 130) and i too was wondering why. Looking at your pic i would say that the "tree line" is very similar too.
Reefmack i think you may be correct about the hood.

 

[imaccat]

Very weird, although I have a much lighter covering mine goes up to the top of the tank, especially on any plastic rather than glass.

The only thing that comes to mind is that it may have something to do with water changes, does the line coincide with the amount of water you take out?

 

[Reefmack]

Iain - that's another good possibility.

 

[soily]

I don't think its that, because i have the 130 when i do a change i take out 25l this drops the water to about an inch and a half below the line (approximately 4" of water removed).

Now we are on that topic i have a few corals that i move to the bottom of the tank when i do a change because otherwise they would be out of the water for a few minutes. Could i leave them alone or am i right to move them ?? The corals are zoa's and a sprig of xenia.

 

[Reefmack]

I'm pretty sure you'd be safe leaving the corals where they are. If the exposure to air is short I don't think it will harm anything. I've seen quite a few tanks with corals growing right up to and a bit above the water line. Just my opinion.

 

[anewguy]

thanks all for the replies. that water change idea sounds very suspect to me. that is very close to where the water level gets to when i change it. ill be doing a waterchange later this afternoon and ill let everyone know what happens then.
soily, there is a video on youtube (sorry cant remember the title off the top of my head)that has a guy showing corals out of the water during lowtide.

 

[Reefmack]

The water change level may be it. Exposure to air usually kills coralline, so that may very well be be why it can't get started up there.

 

[nanoreefing4fun]

That makes sense to me

 

[anewguy]

well, there you go. imaccat you're a genius! thanks all for the help

 

[steved13]

Wow, Great call Iain!!!

 

[Reefmack]

Case solved - good job Iain!

 

[imaccat]

Lucky guess more like it :whstlr:

Interesting why it does it on some tanks and not on others, maybe the length of time that part of the tank is left exposed? or something else?

 

[anewguy]

I figure it took about a half hour to do the water change. doesn't seem like a long time, but then i didn't know what was going on in the first place so I'm not one to take any guesses.

 

[imaccat]

I guess mine is exposed for about the same time, so no idea why its different - add that to one of the great mysteries of life

 

[soily]

+1 to the mystery lol, as i said in an earlier post my treeline is definitely above the level i empty water to during a change. My treeline is just about level with the top of the return nozzels but my low water is a good 2" below that.