I have three acropora, 2 granulosas and one humilis type that have all morphed to a green pigment. The two granulosas started out purple and the humilis looking acropora should be a nice cream with blue tips. Alk is a bit low 7.5, trying to boost with supplementing my regular dosing, things are growing and sucking up the alk. I am not particularly happy with the colors. Po4 are a bit high, .12 so nutrients could be a cause as well. Just curious on people's thoughts.
a few acros going green...why?
- Thread starter slojmn
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NewSchool04
New member
I think you've answered your question. I've found that high nutrients, high phosphates tend to at first discolor acros towards the green shades. Everything starts to look the same color.
NewSchool04, thanks 
, Agreed, I wondered about the PO4's the most. In the past I have had PO4 between .10 and .17 and colors have stayed pretty good...but .04-.06 was always the best. I no longer run the Zeo on this tank and back when it would creep up the Zeo seemed to help hold the great colors. I am running GFO and it is getting changed out today after a month. Maybe I need to go to every 3 weeks. Toying with going back to the Zeo ever so slightly...but I'd rather not at this point. I may need to play with the GFO amounts and times in the canister. I've been very conservative with the GFO. Currently I have mad purple corralline every where but my alk is a bit low so I may be a little out of whack there. I hate to chase numbers though. All the corals, despite some weird green shifts in color for the three are super happy and healthy. I'm adding some supplemental LED's to the tank this weekend but I don't anticipate much better color in the corals from this. I think I need to bring down the PO4's. I do feed really heavy and I have a pretty decent fish load. Soooo, some things to consider, decreasing feeding amounts and increasing GFO over time to see if I can get the Po4's back down in a better range along with increasing my alk by a point or point and a half over the next month or two.
, Agreed, I wondered about the PO4's the most. In the past I have had PO4 between .10 and .17 and colors have stayed pretty good...but .04-.06 was always the best. I no longer run the Zeo on this tank and back when it would creep up the Zeo seemed to help hold the great colors. I am running GFO and it is getting changed out today after a month. Maybe I need to go to every 3 weeks. Toying with going back to the Zeo ever so slightly...but I'd rather not at this point. I may need to play with the GFO amounts and times in the canister. I've been very conservative with the GFO. Currently I have mad purple corralline every where but my alk is a bit low so I may be a little out of whack there. I hate to chase numbers though. All the corals, despite some weird green shifts in color for the three are super happy and healthy. I'm adding some supplemental LED's to the tank this weekend but I don't anticipate much better color in the corals from this. I think I need to bring down the PO4's. I do feed really heavy and I have a pretty decent fish load. Soooo, some things to consider, decreasing feeding amounts and increasing GFO over time to see if I can get the Po4's back down in a better range along with increasing my alk by a point or point and a half over the next month or two.
NewSchool04
New member
Have you thought about using bio pellets? From what I've read, it seems they would be perfect for your system.
I would agree that the green is due to high phosphates. Increasing water changes along with changing out your GFO every other week should get you back in check. At high phosphate level, like you have, your GFO will exhaust quickly. If you have a hanna, you can measure the phosphates on the effluent side of the reactor to give you a better idea of when it needs to be changed. One thing to keep in mind it that GFO will also percipient out your alk, lowering it .
.Brian, Thank you for that tidbit on the alk, I had no idea. I keep upping my dosing minutes on the alk and more recently adding supplemental pops of it to raise it with no success. I know the corals are sucking it up for sure so getting it higher is a priority. I will definitely go to every other week and check the effluent on my GFO reactor to get a better sense of what is happening with my GFO.
Well this is kind of the pits. I just tested my make-up salt water and found the PO4 measurement at .08. Ugggg, I know the water is coming out of the RODI pretty clean as I have two DI stages and I am really careful about changing the first two filters pretty often. TDS always reads 0 after the final stage. I need to get new Hannah reagent powder though...I just realized mine are all expired last year. I am due for a new bucket of salt. Maybe a salt change is in order.
NP Alicia, just remember not to low your phosphates to fast. You don't want white corals. Also the more you changes your GFO the more it's going to effect your alk. I would get your alk higher/ to were you want it before going to the bi-weekly GFo changing. Depending on the salt your using you might need to bring your make-up water up in alk. Might want to test the make-up water too 
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There are a few factor that can contribute to the lower of alk while using GFO. One is the while lowing you PO4-, it will increased calcification in your corals lowing calcium carbonate.
Another is the iron in the GFO will precipitate calcium carbonate. The pH near the GFO surfaces can be higher, this is cause from the iron displacing hydroxide from the surface of phosphate and other inorganic and organic ions. The supersaturation of calcium carbonate increases as the pH rises, driving the precipitation of calcium carbonate.
James404
I <3 Acros
Update, Acros still green, hehehehe. However, I got new Hannah reagent powder for my Phosphate test and found the tank to be .11...it was .17 on subsequent tests with the out of date reagent. The effluent out of the GFO reactor after I replaced with new GFO was .03. All corals look great so there has been no reaction to a bit more GFO in the reactor...a few change outs ago I had a bit of recession on a few corals when I swapped the GFO and felt I was to aggressive. This time everything seems fine a week into the new GFO. Alk is still low despite adding by hand. Corals growing though 
. I will keep at it and go slow. Eventually I will get the PO4 down and the alk up...hopefully the corals in question will shift color over time as params get where I want them.
. I will keep at it and go slow. Eventually I will get the PO4 down and the alk up...hopefully the corals in question will shift color over time as params get where I want them.
THEDLO
New member
im starting to go through the same thing. i suspected that my levels where off how ever my lack of nuisance algae was telling me other wise... heres a current pic of my tank as of a few minutes ago. its hard to notice the affected coral but if u look closely at the top of my rock formation in front of my left overflow i have a tri color valida colony that is brown purple and green lol a little different then it look when i first got it, but it has been growing and pretty fast too. *sigh...
I have the same thing with nuisance algae...none of it . This is a really good thing but leads me to think that all params must be awesome when I'm not testing. I notice you have a lot of purple coralline algae as well, so do I. Its growing everywhere quickly. My mag seems to be in line but alk still is somewhat low and calcium is around 425. All I know is that nothing good happens fast in this hobby and I am going very slow with my attempt to lower phosphates and raise my alk. I kind of wonder about nitrate numbers as well. I am still feeding fairly heavy but I have cut back a bit. The three corals in question are still green. I have noticed some other corals getting better, deeper more vibrant color as they are growing so this is encouraging .
. This is a really good thing but leads me to think that all params must be awesome when I'm not testing. I notice you have a lot of purple coralline algae as well, so do I. Its growing everywhere quickly. My mag seems to be in line but alk still is somewhat low and calcium is around 425. All I know is that nothing good happens fast in this hobby and I am going very slow with my attempt to lower phosphates and raise my alk. I kind of wonder about nitrate numbers as well. I am still feeding fairly heavy but I have cut back a bit. The three corals in question are still green. I have noticed some other corals getting better, deeper more vibrant color as they are growing so this is encouraging .
