Ok so past couple weeks noticing some cyano growth on my rocks. I made a mistake and was putting bad TDS water in for maybe 3-4 weeks from my RODI system. I did a 25% water change last weekend and saw some of the cyano calm down a little. Some of the cyano is growing on my corals, I am scared if i blow it off it will spread more. I checked my parameters no nitrates or phosphates. PH is sitting at 8.09. Calcium is around 400. Running skimmer and carbon 24/7 as well. I run one filter sock and change it once a week. Cant think of anything else to get rid of this issue.
Slight Cyano Issue
- Thread starter jvaleno12
- Start date
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RobZilla04
Well-Known Member
Depending on how bad it is, it'll either pass in some time, or you'll need to take other measures such as additional water changes or utilization of a product such as Chemiclean. You can try using a turkey baster or similar to suck up and manually remove as much as possible to start with. Lesson learned here is don't use anything but 0 TDS RODI for top off and new salt water mix. Also what test kits are you using for nitrates and phosphates. It is not possible to have zero point zero zero zero of either.
mcarroll
10K Club member
Cyano isn't gonna hurt anything in almost all cases. It's just a phase, so try to relax while the tank gets itself sorted out. 
Even if you let it pass without doing anything but siphoning excess cyano out along the way, it would take a while, but that's OK.
Assuming you've addressed the root of the problem, the best thing you can do is siphon it out if it gets heavy....and wait.
I'm not positive that the bad RODI water is the whole story though...let's make sure that any waiting is worthwhile.
How old is the tank, BTW?
Are you doing anything to create the zero/near-zero nutrient environment? Overall that's likely to promote cyano....or worse.
Do you have any other algae growing around the tank? Anything green?
How is your CUC? What's in it so far? ..and do they seem to work on it at all?
Stop doing anything like GFO, extra bio-media, carbon dosing, etc.
You may even want to consider adding some N and P fertilizers to get things moving in the correct direction – thriving instead of starving.
Cyano is always going to have a PO4-source on the substrate, and it doesn't take a lot of PO4 to facilitate growth. It also seems to have superior abilities at acquiring nitrogen for growth, even when nitrates seem to be unavailable.
Those conditions will be favorable to ultra-competetive substrate algae and they will be harsh for things like corals which have a need for phosphate, but have no direct access to the substrate.
Even if you let it pass without doing anything but siphoning excess cyano out along the way, it would take a while, but that's OK.
Assuming you've addressed the root of the problem, the best thing you can do is siphon it out if it gets heavy....and wait.
I'm not positive that the bad RODI water is the whole story though...let's make sure that any waiting is worthwhile.
How old is the tank, BTW?
Are you doing anything to create the zero/near-zero nutrient environment? Overall that's likely to promote cyano....or worse.
Do you have any other algae growing around the tank? Anything green?
How is your CUC? What's in it so far? ..and do they seem to work on it at all?
Stop doing anything like GFO, extra bio-media, carbon dosing, etc.
You may even want to consider adding some N and P fertilizers to get things moving in the correct direction – thriving instead of starving.
Cyano is always going to have a PO4-source on the substrate, and it doesn't take a lot of PO4 to facilitate growth. It also seems to have superior abilities at acquiring nitrogen for growth, even when nitrates seem to be unavailable.
Those conditions will be favorable to ultra-competetive substrate algae and they will be harsh for things like corals which have a need for phosphate, but have no direct access to the substrate.
