coralline algae tunring white

[slacroix]

my reef tank has been up for about a year. at the beginning, all live rock turned purple with coralline algae. recently, however, in some areas, that coralline algae is turning white. it also appears that the zoanthid colonies are retreating from that white coralline algae. here are my specs: 40 gal breeder with 60 lbs live rock, actinic and metal halide light (150 W). the only recent change is that we replaced the metal halide lightbulb. any idea why the coralline algae is turning white and what it means?

thanks, sean

[JennM]

What are your water parameters? Specific gravity, calcium, alk, what kind of salt are you using and how often are you doing water changes?

I've brought tanks "back to life" when they were totally devoid of coralline from bad care or neglect - but to start with one needs to know the chemistry and "fix" any problems there.

Sounds like your coralline is dying off. If you just changed the bulb it's not unusual for some corals to be a bit ticked off while they adjust to a brighter light, but that usually doesn't kill off coralline in my experience.

More info please, We'll help you figure it out.

Jenn

[JennM]

Where are my manners???

WELCOME to TRT!



Jenn

[slacroix]

thanks jenn,

water parameters-
sg-1.026
temp 79-80
calc- i dont measure it, but use kalkwasser about 2x per week.
salt-instant ocean
alk-has laways run a little low. at the very low end of the acceptable level. i have not buffed becasue my ph has been good and stable.

all other corals appear to be doing well, particularly under new light. coralline algae growth on walls really improved under new light. but in one section of tank, it started turning white.

[slacroix]

oh yeah- i forgot. we do water changes about every two to three weeks. they are usually about 10% water changes.

thanks for the welcome. this is a great site.
sean

[JennM]

Hmmmm - could anything be eating the coralline in that spot? Urchins do a good job of that.

I have found that in tanks where the calcium and alk levels were consistently good, but coralline was slow/nonexistant, the addition of some Magnesium really helped. You might want to have your water tested for Magnesium, or experiment a bit with an additive. I use Kent Tech M, and have noticed a huge difference in one particular tank I maintain, when I took it over in April of last year the only purple in the tank was cyanobacteria but with lots of time, patience and TLC it's looking awesome now with a sea of purple coralline. When I got the calcium and alk stabilized but still saw no coralline, I asked some questions and was advised to try the magnesium. Since I'm the only one who doses this tank, every other week (fish tank owner is not a hobbyist, just likes the purty fishes), it took a while but on the 6th week we had a dime-sized patch of coralline (Alleleulia!), two weeks later, 4 dime sized patches, 2 weeks later more quarter sized patches and so on.

Might be worth a go.

Jenn

[slacroix]

thanks for the advice. i'll look into magnesium and keep an eye on the coralline. i kinda thought it "looked like" it was dying off, thas why i was concerned.

cant imagine whats eating it. no urchins, just snails, hermits, a 6 line wrasse and a percula. also a sea star and a hitchhiker red eye crab that i cant find let alone get rid of.

thanks again for all your help! i'll let you know how it turns out...
sean

[Flatfish]

If the patches of white are small and localized (or maybe just one small patch?). Then just like JennM mentiond, something may be eating it. I have a small scallop-like creature about 3/16" in diam.) in my tank that regularly leaves stark white patches in on my rock. It took me a little while to spot is because it was covered in coralline. It's still in there along with a pencil urchin they both leave scars, but they can't keep up with the corralline growth.

[JennM]

Changing the subject a bit (aren't we notorious for that, Jerel?)

Getting rid of the crab is relatively easy. If you know what rock he hides in, take a tall drinking glass, set some smelly bait in it and sink it in the tank after lights out (so the fish don't take the bait). Set the glass upright, but lean the lip of the glass against the rock where you've seen the crab. Go to bed. In the morning, the crab will be there in the glass for you. He'll jump in to eat the bait but cannot get out. I've cought about 6 nuisance crabs in my reef this way. Sometimes it takes a couple of days but most times I get them overnight. Once I saw one crab in a rock, set the trap that night and the next day I had caught TWO hitchikers! and that was well over a year since I'd added any new rock to the tank! They live happily ever after in my sump.

Jenn

[ChrisC1029]

Slacroix, I think all of the above are good comments. The only thing I would add, is to measure your calcium. You mention that you don't measure calcium and your alkalinity has always been low, at the very low end of the acceptable level. I can't remember where I read it, but IO salt is relatively low in calcium, somewhere around 330-350 ppm I think. I used to use it also, but swithched to Kent after reading that. So even with your water changes, your starting off around maybe 350 ppm on calcium. Most people recommend keeping calcium in 400-450 range. Kalwasser typically will keep you where you're at re: calcium and alkalinity, but unless you're adding very large amounts (which will shoot your pH way up), its not going to bring your calcium up from your 350 ppm starting point. So depending on what the calcium demand in your tank is, your calcium might be drifting down ward if the amount of kalkwasser isn't meeting that demand. My guess is your calcium is low and maybe magnesium too, and you will probably need to bring it up with a calcium chloride additive such as Turbo calcium.

However, if you're experiencing coraline die off (and if its actually turning white and not being scraped away, thats what it sounds like to me) I don't know that I can explain why its occuring in patches, if calcium was the only problem. l

[Spanky]

the only recent change is that we replaced the metal halide lightbulb.

Sean, WELCOME

How old was that light bulb? Sounds like it's bleaching because it's getting more light and low alk. Get that alk up.

Changing the subject a bit

Who us??

Jerel

[Junkzoo]

Ditto on all the great prior posts,,in my experience,,a dose of Magnesium did the trick after a long head scratching period,,,,,HTH