hmmmm not sure if 'clumps of white stuff' are algae or not....... can you take some photos to help us ID it. No point us telling you how to reduce algae if that's not the real problem.
you say you've added an anti-bac med for finrot.... so you're obviously having some problems with the tank, you also said it's a new tank..... all this leads me to think the tank is probably cycling, have a read of the link in my sig 'whats cycling' which should explain it all and tell you what to do.
back to the main question though, here's my spiel on algae....
Algae like any other plant needs 3 things to live, CO2, food and light. You'll have lights in the tank and the tank may also receive direct sunlight so this gives one factor, the fish's poop effectivley becomes compost and gives food to the plants and there is always some CO2 in the water. If you have any body of water where you have all of these things then you will get some algae growth. However these are also the same things which make any live plants in your tank grow. Every plant and type of algae has different requirements for the amount of CO2 food and light they need. You can quantify this for the purposes of explanation as follows (the quantification isn't real, just representative to help explain). If your water naturally has 10 parts of co2, food and light, and the plants that you have need to use 10 parts of co2, 7 parts of food and 6 of light, once they've used this up they then can't make use of the left over food and light because there is no CO2 to go with it, this is where the algae comes in, it's much less demanding than the plants and as such can use up the remaining food and light with only trace amounts of CO2 and as such you'll get algae growth.
Essentially when people go for live plants in their tanks they aim for one of two methods, either 'high tech' which is where they add CO2, food and lights in such large quantities that the plants have everything they could possibly need and more, the plants then outcompete the algae and as such you just get good fast plant growth and very little algae. the second option 'low tech' is where you aim for the right balance of co2, food and light but only in relativley small quantities, the plants use it all up, grow relativley slowly but because you've not got 'left overs' the algae can't really take hold.
Now realistically, we all get some algae, you just need to scrub the glass to remove it or pull it out depending on the species of algae. However if you are getting a lot of algae growth then you need to adjust the balance of CO2, food and light getting to your tank so that you achieve a better balance and the plants get it rather than the algae. It's not an exact science as there's a lot of different factors, you generally just have to tinker until the algae dies back.