Algae, Nutrients, and Sunlight


Premium Member
Ok I know your views on this topic for the most part Mr. Calfo but lets put an example to test and Im interested in your opinion. Lets say we take two tanks same nutrient, same size tanks, same skimmer, same amounts of algae (to start with anyway) but you put low lighting on one tank and high lighting on the other tank, would it be fair to say that the high lighting tank would have the algae consume the nutrients much quicker? I know there are other variables at play such as chemistry makeup, and types of algae, but lets say for the majority on types of algae and same chemistry. I do see controlling algae growth more ascertainable by controlling your nutrient load but as you know sometimes we have to hit problems with more than one angle.

BTW Thanx again for coming down to see us southerners....everyone is still talking about all the ideas you put into their heads!

For the sake of the argument and with the other parameters set forth and standardized, I would agree that the tank with brighter light is more likely (with most species of nuisance algae) to afford more vogorous growth.

Still very true that even in the brighter light scenario, much of the "extra" growth could still be limited by nutrients. I have seen enough aquarium in full sun for 5 or more years ;) that were free of nuisance algae for having had due diligence to nutrient control issues.

And my pleasure BTW visiting y'all down in FL :D I really had a great time. Looking forward to a return during cooler weather though :p

Ciao, bub

interesting question

interesting question

So, could your question be rephrased as-does high light algae in a high light condition consume more nutrients than low light algae in a low light condition? All other things being equal I don't see why this would be the case.-Jim
Frankly... I don't see the point of the questions (Jim or Rocky) :p or what useful tidbits we can even glean from it based on vague theory.

Heehee... really fellas. Lets get more specific here or just go watch the first NFL preseason game... on the tele as we speak :D
Anthony Calfo said:
Frankly... I don't see the point of the questions (Jim or Rocky)

My point was for someone who is dealing w/major algae problems to tackle it with their nutrient controls first, but if still need be control the lighting as a latter resolution, maybe even a much latter resolution. Im so used to going after predators that prey on specific algaes and have since learned that controlling the nutrient levels is easier, because the nutrients are still there they just change formats (algae into detritus). Just trying to get the priorities lined up thats all, im not debating the approach that nutrient control is a better way to control algae then lights.
Ahhhhh... gotcha! Well stated, and yes - very, very much agreed.

Nutruent control really is the primary limiting factor for most nuisance algae. I haven't see a "plague" that literally could not me knocked out in 2-4 weeks with due diligence.



Also it would appear that Anthonys' answer indicated that higher light species of algae are actually more efficient at nutrient uptake than lower light species. I doubt this is true since the growth rate (nutrients converted to algal mass) seems to be similar between fast growing high light algae-say halimeda incressata, and fast growing low light algae-red gracilaria perhaps.-Jim

Your inference is incorrect and the very reason why we (I at least ;) ) need to resist spending time on vague virtual theories/questions.

There was no mention of high light species versus low light species. Simply algae with the same nutrients and all other params standardized save for more light. A stimulus.

Lets drop it, bubs... really a minor point. We can all agree (or ignore if you like :D ) that nutrients are a significant limiting actor in algae growth.

Not to kick a dead horse, but... perhaps from a practical standpoint, if you have a refugium containing algae and an algal bloom in the display tank would it be a benefit (while tackling the underlying nutrient issues of course your primary goal) to decrease the photo period in the display tank while increasing it in the refugium where you can agressively harvest the algae? In a sense using the algal scrubber concept through your refugium?

(Sorry to reopen this stream if all are tired of it :rolleyes: )
The premise of your suggestion is basically correct Ron, but misses the bigger picture.

decreasing light in the display assumes that the nuisance growth is more limited by light than the featured animals are dependent on it. More speifically... that the system will benefit more by suffering the corals and other desirable phtosynthetics with the algae (if it suffers at all) versus their ability (given proper light) to outcompete the algae.

The truth is that nuisance algae often gets worse, as we know, with less light (decreasing photoperiod), or (most commonly) as lamps age or become dirty. We lose the benefit of the large mass of corals and good algae competing in good health with bad stuff ;)

Savvy aquarists often observe that with improved control over nutrients and improved light (cleaning lamps & lenses, new bulbs, better water clarity with carbon/ozone, or simply longer photoperiod if previously deficient) that the algae wanes faster!

For the overwhelming majority of nuisance growths... its all about nutrient control.

Good brainstorming though... kind thanks for your input. :)

Thanks for the reply. I guess the bottom line is tip the scale in favor of coral...nutrient poor environement, intense lighting, high flow, remove detritous etc. Makes sense from an ecological standpoint, as with natural reefs, algae is I suppose always waiting for the opportunity to out compete based primarily on environemental conditions frequently provided by us.