Rex's Planted Tank Guide

Your Source Of Information For Planted Tank Aquariums, Lighting, CO2 & Fertilizers


Here is a summary for those of you who are in a hurry and don't want to read the entire guide.


  • 2 watts per gallon on tanks 30 gallons and up is a good starting point.
  • It's not how much light you have over the tank but how much you get INTO the tank.
  • Actinic light doesn't do a whole lot of good for a lot for a planted tank. You should be looking at bulbs with a K rating of around 5000k to 10,000k.


  • Coarse sand/fine gravel with a grain size in the range of 1-3 mm works best. Larger than that can cause problems with some plants and almost all ground covers. Smaller than that can compact.
  • If you are going with coarse sand/fine gravel use a fine layer of peat moss under the substrate. You should still be able to see the glass. Also adding a layer of laterlite will help. If you have access to mulm from an existing tank put a thin layer of that down also. Mulm is the stuff you vacuum from the gravel.
  • If you can afford it then one of the higher tech substrates such as Flourite or Eco-Complete work quite well. Flourite can be mixed with coarse sand with a similar grain size. Use at least 50% Flourite based on depth of the substrate.

Water Chemestry

  • Don't use any acid or phosphate based buffers to try and lower pH. If you need to lower pH then CO2 is the way to go.
  • RO/DI water is not needed in a planted tank in the vast majority of cases.
  • If you need raise your kH use baking soda.
  • If you need to raise your gH then use Epsom Salts and Calcium Chloride.

Test Kits

  • Iron test kits are a waste of time and money.
  • Good test kits cost money and are worth the price.
  • If you dose your tank and your test kit shows no change then suspect the test kit.
  • Don't test your test kit in your tank.


  • Bulk chemical fertilizers are about 44X cheaper than commercial products.
  • Bulk chemical fertilizers are safe.
  • If you have questions about the use of bulk chemical fertilizers read Fertilizing The Planted Tank.
  • Don't blindly add bulk chemical fertilizers without knowing what you are doing. They are extremely concentrated.
  • There are some absolutes when using bulk chemical fertilizers. ¼ of a teaspoon of KNO3 will always raise 20 gallons of water by 11.25 ppm.
  • When dosing bulk chemical fertilizers always make sure that you understand there is a difference between tablespoons and teaspoons. Always use measuring spoons as there is no standard when using normal silverware.
  • Your best bet is to get an inexpensive digital scale and use it. You can normally pick one up off of EBay for around $20.
  • Suggested nutrient levels are Nitrates 10-20ppm, Phosphates 1-2 ppm, Potassium 10-20 ppm, Iron 0.5-1.0 ppm.


  • CO2 will help with plant growth at all light levels.
  • A constant level of CO2 will contribute to plant growth and help control algae.
  • A constant level of CO2 is hard to obtain with DIY rigs.
  • Don't add CO2 if your kH is less than 3°.
  • Suggested CO2 levels are 20-30 ppm.
  • CO2 injection is a must if your light levels are high.
  • If you go with DIY CO2 use juice bottles instead of pop bottles. They are less likely to tip over.


  • There is no need to do a “fishless” cycle on a planted tank. Read the Cycling section of the guide.


  • Good hardware is an investment. Spend money right the first time to save money in the long run.
  • Wider tanks are better than narrow tanks. The standard 55 gallon tank sucks. It's only 13” wide. A 75 gallon is a much better choice at 18” wide and a 90 gallon at 24” wide is a wet dream!
  • Try and stick with tanks that are in lengths of 2, 3, 4, 6, or 8 feet. It's much easier to find lighting solutions for these tanks than it is for 30” long or 60” long tanks.
  • Make sure that you can reach the bottom back of your new tank on the stand. If you need a stool and still can't reach the bottom back then get a lower stand or a narrower tank. Having to go diving to work in the tank is not fun.
  • Canister filters are preferable for tanks over 20 gallons.
  • Try and avoid filters with Bio-Wheels as they cause excessive CO2 loss.
  • Heaters with remote adjustments are better than those you have to get wet to adjust. Stay away from cheap heaters. If you have a large tank and use dual heaters think about investing in a temperature controller.
  • Substrate heaters are in “my opinion” a waste of money.
  • A UV filter is not a necessity.
  • A RO/DI unit is not a necessity for 99% of the people in the hobby.
  • You can build a lot of the hardware you need for your tank. Think bubble counter.
  • That brace in the middle of your tank… It's there for a damn good reason. Don't remove it unless your homeowners or renters insurance is paid up.