High phosphate with low nitrate = cyano?

[robert]

I set up a new 70g frag tank a few months back, bare bottom, sump and skimmer, spray filtration over bio-balls.

Long story short - I added a few pieces of BRS macro-rock which leached phosphate badly. Interestingly, despite having zero nitrate - I developed the brown slime algae and surprisingly - cyano.

Checking around I read about something called the "Redfield Ratio". Apparently in freshwater lake management its known that an imbalance of phosphates and nitrates, where phosphate is higher, cyano develops and it can be addressed by increasing nitrate in the system. Some freshwater planted tank enthusiasts monitor and maintain the phosphate/nitrate ratio to keep cyano at bay especially when running denitrators.

Thinking about this, it makes some sense as I read that cyano is able to fix its own nitrate whereas normal algae is not. GFO is the obvious answer, but in a new set-up which could leach excess phosphate for a while, might the addition of low levels of nitrate - ca/mg/na nitrate be an answer? Could tanks with chronic cyano be treated with a little excess nitrate?

I've dosed the frag tank with both mg-nitrate and ca-nitrate to bring the level up to 2.5 ppm. I also hit it with some chemi-clean - so the cyano is gone regardless.

I just thought I'd throw this out there (it was new to me) and would be interested in any thoughts you all might have.

 

[knockout]

interesting idea, would have like to see the results without the use of chemi-clean, it will be difficult to assess the effectiveness of the addition of nitrates into the system

 

[KSzegi]

Interesting thread for sure - am also curious to hear others opinions and experiences.

I think if the 'cause' of cyano was that simple it would not be such an issue for so many! And it doesn't explain why low nutrient tanks still get cyano and tanks with very low phosphate and higher nitrate get cyano. Cyano is so resilient and opportunistic that I believe it shows up anytime there is an imbalance of what we think of as the 'good' bacteria in the tank - amongst other potential reasons for it to get a foothold! Perhaps an 'unbalanced' ratio either way or very low nutrients could all limit the amount/variety of beneficial bacteria and/or even algae in the tank therefore eliminating competition for the cyano.

I had a recent issue with cyano .... and in my instance the phosphate was low - readings of zero on the hanna meter but nitrate was higher at about 15. So at least in my case compared to yours ..... I don't think raising nitrate levels would have been the answer. I feel that in my instance part of the reason is also that it is a fairly new set-up - was an upgrade to a larger tank - so even though most of the rock was from an established tank, there was all new sand, new rock additions etc and the tank will take 6 months to really reach an equilibrium. My flow is good - and interestingly enough my cyano was not appearing in what I would consider the lower flow areas of the tank. After doing all of the 'usual' things - siphoning out, water changes on a several times per week basis etc .... I treated with zeovit coral snow and zeobak ..... which cleared it up. I then had some small patches coming back ..... and I did the lights out treatment and a large water change - and will continue with the zeo coral snow. Currently all traces of cyano are gone ..... water parameters have remained the same other than the nitrates have decreased slightly.

As knockout said though ..... would have been interested to see what would have occurred in your instance if you had gone without chemi-clean and had just increased the nitrate level ..... would it have just given the cyano more fuel or would it have increased the beneficial bacteria population enough to outcompete it ..... or as your tank stabilized would it have cleared ....

 

[MattL22]

Similarly in my tank I have a no3 testing at 0 but po4 testing a tad high and I have this film alage on my rocks I can't beat I run a ton of gfo carbon even using phosguard in a media bag! I just picked up the new product by red sea no3 po4-x which is a forum of vinegar dosing but I'm wondering if carbon dosing will worknwith 0 nitrate present??? Should I actually feed heAvily to try bring up my no3?

 

[robert]

I've been reading a bit more - this is actually pretty well understood and put into practice with planted freshwater aquariums. I know it isn't the answer to every situation, but I can see it's potential application to our hobby. - not just with regard to cyano - but perhaps with optimizing growth rates.

Matt - I really can't answer definitively - but yes, redfield ratios would suggest that you would want to keep to the 106:16:1 ratio - too far outside of this destabilizes the nutrient balance and unwanted algaes/bacteria can dominate.


As an aside, after I decided to up my nitrates a bit, I needed to find a source of good clean nitrates free of metals and what-not. I considered home depot the health food store etc, but I really wanted something pure so I hit on the idea to check out the hydroponics store a couple of blocks from home. Understand, this is northern California where it is not uncommon to see sign-wavers on the corner for the latest opening medical marijuana clinic on any given Saturday. Hydroponics stores are pretty common.

It was a little weird but I went in. The place felt strangely comfortable. Metal Halide bulbs, leds florescent fixtures, rows and rows of chemicals...

The guy that came up to help me listened to what I wanted and why I wanted it. I told him I was growing corals and he though that was cool and actually knew a heck of a lot about what he was selling. He recommended some stuff which I rejected, but which in retrospect (having read more) was really worthy of consideration.

I got a couple of different nitrate sources and was at the counter checking out when the clerk looked up at me and asked for the name of my business. I told him I kept a marine aquarium and sold and traded coral frags. He then said that all he had to do was enter a business name and that I'd get a discount - Oh well a discount is a discount - I thought for a moment trying to come up with a name for my business. - Ah I got it - Robert's Reef. He looked at me puzzled for a second.

I was looking over his shoulder as he typed it in - Robert's Reefer - my heart skipped a beat - **** - I hope that doesn't flag someone to check my electric bill - if so I'm screwed. - Oh well I took the discount. lol.