Epiphany: Plants don't die because algae attacks them, algae attacks them because they are dying?

[cubequeen]

I've kept fish for many years and am good at keeping fish alive, but consistent plant growth still eludes me most of the time. I've had periods of lush growth, but I still can't tell you why. The worst thing is algae growing on the plants, even when there is almost none anywhere else. One thing that's confusing is that for every person that says algae is caused by excess nutrients, there is someone that says that is not true or that you actually need to add MORE nutrients. I have visited a couple of UK sites lately and they talk about how starving, dying plants "jettison" or leak ammonia, sugars and other nutrients. So algae gloms onto those nutrients and grow on your plants. I thought, "Here is something that finally explains how I can have so much algae on my plants even with low nutrients and very little algae elsewhere." So my conclusion is that plants don't die because algae attacks them, algae attacks them because they are dying, like scavengers on a carcass. So I will be upping my fertilization a bit and see what happens.

 

[smitty]

Let us know the results of your findings after you add more fertilizer. This is definitely a post for me to watch, thanks.

 

[Kaliska]

You need a balance of nutrients. Algae is caused by having 1 or 2 excess nutrients. If you have too much phosphorous but not enough other stuff for the plants to use they won't grow as well but algae is less picky. If you have high nitrates same thing. If you have high silicates you get diatoms or brown algae. Adding fertilizers does help because it boosts everything to match so the plants can use whatever amount of phosphorous or anything else your tank has. Old activated carbon that hasn't been changed will leach phosphorous. You also have to balance light with how fast your plants can grow and how many nutrients you are pumping into the tank for the plants to use. At some tipping point you need co2 injection or the plants just can't keep up with how you are feeding the tank (both fertilizers and light).

 

[SnakeIce]

One nutrient being High is not a problem, if and only if the low nutrient/s do not hit zero. It has been tested in plant only tanks with high light, high CO2 that phosphorus and/or (insert nutrient of choice) to *ridiculous levels do not cause algae when there is also consistently enough of the other nutrients.

*(50 ppm phosphorus, or 120 ppm nitrate for example)

The source of that conclusion in error being that algae does gain that entry when nitrate, potassium, etc or some micro-nutrient hits 0 for some period in between your dosing schedule. Thus the rational behind Estimative Index fertilization. You dose more than the plants can possibly use for the week under optimum conditions and do a 50% water change before dosing again to prevent measuring error and or residual levels from building up to far. This EI dosing is based on having CO2 at 30 ppm for best results, but the basic idea still holds for low tech aquariums although the plant growth is not as vigorous and thus there is more time for algae to get attached to plants in your tank.

 

[Greggz]

Is your tank low or high tech? Injecting pressurized co2? Having had both low tech and high tech tanks, there is a big difference.

In my experience, the main cause of algae in a low tech tank is too much light, both intensity and duration. I don't think adding more ferts will help, as without co2 you won't get the growth to keep the algae at bay.

When I first went high tech, and added co2, I started getting some algae. Then I started adding more ferts, dosing EI method, and added more light. Plants started growing very well and little or no algae to speak of.

Having had both, low tech and high tech tanks have very different needs. Tell us more about your tank and how it goes.

 

[cubequeen]

Well, to give a little bit more information, I'm not sure I'd call my tank high tech. It is a 29-gallon cube. I currently have 48 watts of T5 HO lighting. I used to have 96 watts, but concluded that was too much light and have had less problems with most algae since reducing the lighting. I am dosing sort-of Perpetual Preservation Pro, but judging by the amount of nitrate present since I have a nitrate test kit on hand, the levels were a bit low so I'm increasing that to about 1-1/2 times PPP and have just re-started DIY yeast CO2. I do approximately 50% water change most weekends. I'm also currently pretty low stocked with fish, three Buenos Aires Tetras, three adult cory catfish and one juvenile cory. I also have very few plants, but am trying to get the ones I have to grow. I know it is advised to plant heavy from the get-go, but I spent a bunch of money on a shipment a few months ago and what the Buenos Aires didn't eat, all melted. I think my mistake was not supplying all those plants with heavy fertilization and CO2 as soon as I put them in. I'm betting the grower probably grew them with heavy fertilization and CO2 and they couldn't adapt to the sudden change to my tank without those provisions.

My concern is not so much with algae in general, but with algae that grows on the plants even when there is not so much elsewhere.

 

[SnakeIce]

Have you calibrated your test/s? Even professional tests have to be compared with a set solution to calibrate them. Hobby grade tests need calibration even more so. Make a solution with a known concentration and see what the test comes out with against that. If you are testing and the results are off due to calibration error that could throw a monkey wrench in your hypothesis on what is going wrong.

 

[Greggz]

IMO you are answering some of your own questions, and you are on your way to high tech.

Yes, 96w was way too much light, and even 48W T5HO is quite a bit.
And yes, plants that came out of tank with high light, ferts, and co2 generally won't do well without all three.
And yes, more plants are better. Lot's more plants. Loaded with plants is best.

It sounds like you already know what you have to do. Get the co2 going, add more ferts, and create a healthy home for plants when you buy them. Then load it up. Get some fast cheap easy growers to help get started (Water Wisteria?) , and some fast growing stems like Ludwigia Repens. Your Hygro should respond well, but the S. Repens wants it all, so everything needs to be dialed in. I wouldn't add difficult plants until you get some other ones really growing. Healthy growth is the best defense against algae.

And one more thing. Plants like flow. Have a nice turnover and maybe a circulation pump. Stagnant water can lead to Algae. Plants gently waving in the flow is a good thing.

Good luck and I hope you get it all worked out.

 

[cubequeen]

Thanks everyone for your input. Anyone following this thread, please note that it will probably be a few weeks before I report back on my results. I mainly just wanted to put out there the premise that algae attacks starving plants and that that could be an explanation why algae is on your plants for anyone having this issue.