Bugbear wrote:

I just finished planting a 75g tank a little over 3 weeks ago and am
wondering how to tell when plants have used up all the nutrients in
the water. The tank has basically already cycled do to pre-existing
bacteria from the filter. I have new growth on the plants but am
noticing a kind of brown algae forming on the leaves of some. I know
brown algae is common in a new tank but was wondering how I could get
the plants to out compete it. Currently houses 2 otos, 3 SAE, 1
rubber pleco, and 12 amono shrimp and 5 rainbows. 7-10 days in
between water changes, pH ~7.2. 210w of compact lighting on for about
11 hrs a day. Pressurized CO2 injected as well. Onyx/flourite mix
substrate.

It soulds like you have started right-good lighting, good substrate, CO2,
plants and algae eaters. Good job!


When should I start fertilizing? Should I instead look into
purchasing more oto's as I know they relish brown algae? Also am
getting green spotted algae on the glass or should I adjust something
for now and fertilize a little later. Its a beautiful tank now and
would really like to keep it this way.

Here's what you should look at:

1. Make sure your have LOTS of plants. The more fast growing and healthy
plants, the less opportunity for algae to get a foot hold.

2. As far as WHEN to start fertilizing, since you don't want your plants
to start suffering before you start. Start standard PMDD immediately!

3. Regarding deficiencies, hopefully you don't have any, but here's a good
diagnosis site:

http://www.csd.net/~cgadd/aqua/art_plant_nutrient.htm

Click here too:
http://www.csd.net/~cgadd/aqua/articles.htm
http://www.thekrib.com/Plants/