I think the apparent contradiction of thoughts is coming from the generic use of the word "nutrients." What I have observed is that certain nutrients contribute greatly to algae growth even in small concentrations (like ammonia, or whatever it is that comes from rotting debris/plant matter/food), and other nutrients you can dose and overdose and will never induce algae no matter what you do (such as nitrates and pretty much everything else that is on the fertilization list for planted tanks). This is why one of the standard routines for eliminating algae is to do water changes and vacuum the gravel well, and then dose fertilizers. You're thereby removing the "bad" nutrients and dosing the "good."

What I've come to the understanding of is that algae is opportunistic, more along the line of a parasite than a plant. If the plants are healthy and don't have deficiencies, algae will rarely ever grow on them unless lighting is far too high (or light:co2 ratio is out of whack or changed suddenly which would end up manifesting a carbon deficiency). If the plants are weak, algae moves in and starts taking over much like disease will overtake fish that are in a weakened state.

The need for stability of the light:carbon ratio has proven to be probably one of the top three things I've learned that has helped me keep successful planted tanks with few algae problems. Anytime you have a somewhat dramatic increase in light or corresponding decrease in co2 the plants have to work hard to adapt, and melting leaves, holes, algae problems, and leaf loss are some of the results of this. Keeping co2 and lighting stable and not increasing light or decreasing co2 quickly will help eliminate these issues.

Much of that sounds reasonable, but I think that your last two paragraphs sort of contradict what you said in the first paragraph. Or am I not understanding?

Bill

This thread is very informative but I had a question regarding Ramis's current situation.

I agree that his tank not being planted enough/not having enough fast growing plants to act as nutrient sponges is leaving a lot of nutrients for the Algae to utilize. This explains the presence of algae. However how would one explain the fact that some of his plants don't seem to be doing so well? Sufficient lighting plus plentiful nutrients (presumable not high enough to inhibit plant growth) doesn't seem like something that would cause issues with growth?

I'm curious about what the possible explanation would be for this. Could this be caused by insufficient CO2...the need for which is being generated by the extra lighting? (although his lighting doesn't seem to be all that high).

PS- I'm a noob with no experience with planted tanks . I'm just trying to learn as much as I can as I find this very interesting and I will be starting my 10g planted tank in a few weeks.

Oops, I just noticed that he isn't dosing traces. Could that be a reason? Although with a newly setup tank/eco complete substrate shouldn't it have enough traces atleast to initiate plant growth for a few weeks/months?

Good questions, Orion.

I think dosing micros should be done, although as I said earlier, maybe once a month.

The tank really doesn't have enough light, as the picture shows. The mass of plants that take up half of the top are shading much of the lower part of the tank.

As Vaughn said, 1.6 watts of A + H's lights are plenty for such a tank. However, Ramis is using T8's, which produce (maybe) about 2/3 of the light energy of the higher intensity lights.

So, I'd heavily prune the plants in the center, cut back the nutrients, and if that doesn't work, add a little more light.

I'm sure that there are other approaches.

I'm off to add more nutrients to my daphnia food jars, to get more green water growing.

Bill

I can see what you mean. I'll clarify what I meant a little bit.

Ammonia (or excessive organic waste) tells algae to START growing. Healthy well adjusted plants tell algae to STOP growing.

In the first paragraph, too much ammonia/organics can tell algae to START growing. Even if you have healthy plants - BUT it won't grow on healthy plants. It will grow elsewhere in the tank. The fact is, if there were enough healthy plants in the tank, there wouldn't be an ammonia problem to start with. Ammonia is the only nutrient that I know of that plants do need to compete for against algae.

In the second two paragraphs, healthy plants tell algae to STOP growing. If a plant is not healthy, even in the absence of ammonia you will see algae growing directly on that plant, whether or not there is algae actively growing anywhere else in the tank.

What do you add?

I agree that the lighting might be part of the problem. I have low lit tanks and it can be a challenge to keep the lower plants well lit. Light deficient plants will definitely develop algae. It may work better to rearrange things and stick with lower light plants in areas where you don't have as much light. Some plants simply won't grow without high light, algae develops on them as a symptom of their deficiency.

Also I think you need to do water changes and vacuum weekly to remove organic waste that will throw off your system since it's still in it's infancy. This will enable you to do proper dosing of nutrients. You don't need to do 50% water changes, you could even just go 25% or so and dose lightly. In a new tank you will likely be building up some amount of ammonia in areas where you have decomposition, which will stimulate algae growth. After the tank is 6 months old or more it will be more stable and forgiving and you will likely be able to slack off a lot with water changes.

Might be better to speak in terms of "germination of algal spores".

What causes spring flowers to flower and grow?
They have nutrients etc as do most plants.

Temp is one factor.
Water is another.
Increased light time is yet another.

Now apply it to algae.
What occurs in spring?

1. Warmer temps.
2. More light(more than 10-12 hours)
3. Influx of nutrients from the land(generally lowering O2, adding NH4, adding CO2)
4. Sediment turnover, mixing in the water column(think pulling up plants, trimming etc and then not doing a water change thereafter)
5. Changes in the KH/nutrient levels

In our tanks, Temps are stable, light is somewhat stable, no influx of nutrients really, sediment turnover, sometimes......., changes in the CO2 level sometimes...........CO2 variations and O2 variations........very often occurs..........

High fish to plant ratio(more NH4- this can be good or bad depending on how much plant biomass and how well it's growing, Zeolite, water change routines, type of fish, feeding routines etc).

Unfortunately, some assumed it was this simplistic model => excess nutrients caused it.

Careful observation of a lake or stream over the seasons will tell you far more than most anything you read on the web.

You'll note I go to many places seeking aquatic plants and taking pictures.
We can learn a lot from nature, but folks need to look and observe the places where aquatic plants grow well over a season and then test and see.

Then you get your answers, and generally more questions to be asked.

Regards,
Tom Barr

As I understand it, excess ammonia (ammonia that is not consumed by the plants) "sends a signal" to algae to start reproducing. But I don't think that healthy plants send a signal to algae to stop reproducing. It is the absence of a "start" signal that does that.

Even in healthy, well-planted aquariums, algae does grow on some slow-growing plants, such as anubias. And once some kinds of algae get started, it is extremely difficult to get rid of them, even though whatever condition that got them started had long been corrected. I'm thinking of some kinds of hair algae and BBA.

(If adequate nutrients and a lot of growing plants were all that were needed to control algae, one would not see so many recommendations here and elsewhere to use SAE's and Amano (swamp) shrimp to control it.)

I think there are a number of factors, alone or in various combinations, that contribute to the growth and/or maintenance of algae. I do agree that excess ammonia causes algae blooms.

Bill