if you are wanting instant results then the above is the amount you will be spending. However, i doubt you have a bare bottom tank with no decor so you can deduct much of it due to that. Also depending on what filter you are using i wouldnt want it too close to my intake pipe unless you cover the intake with filter sponge or similar since it will clog the impellar. My bet is you will be looking around $15..... dont forget this stuff grows so spread it out and watch it fill the gaps in no time ! Good luck they can look great .