If you have an aquarium, you are probably familiar with the term green water. It usually turns up at the most inopportune moments, the night before the in-laws arrive or when you are having friends over. It is annoying but the good news is that it isn’t harming your fish. Some of them might actually like it.
Yes it’s annoying, Yes it’s ugly but keep it real. It isn’t harming anything except your pride.
Green water is simply an algae bloom caused by single cell algae and is an indicator that something is out of kilter in the water chemistry and if you want to get rid of it you need to test, test and test again until you have determined what is wrong.. It is always worthwhile having a full test kit ready for these occasions.
Algae control is nutrient control.. If you’ve been researching this you have probably come across that phrase once or twice. If you have an algae bloom it can be caused by a number of different factors or a combination of them so you need to find out what the cause is and deal with it. This is what makes green water so frustrating because it could be a single factor or it could be a combination.
There are several things you can try to rid your tank of green water Canister Filters.
Make sure that there isn’t too much light coming into the tank. I once got green water because one end of the tank got direct sunlight for two hours as the sun went round. Three sunny days was all it took.
Use a phosphate absorbing material in your filter if its available
Reduce the amount of light, less time or intensity or both.
Cut down the food and make sure that it’s all getting eaten.
Vacuum the gravel to remove all fish waste.
Check your fish stock levels. It may be that as fish have grown you have inadvertently overstocked your tank.
Use a fine filter and do more water changes for a while
Add fast growing plants which will compete with the algae for nutrients
Add CO2 which will encourage plant growth stealing food from the algae
Cut back on fertiliser for a week or two
Add some floating plants
Things are different for a planted tank. Use any of the above but don’t resort to Algaecides and black outs as you can with an unplanted tank or you are likely to harm your plants.
Controlling green water is about nutrient control, depriving algae of the nutrients that they need to grow so either reduce the nutrients by putting less in or deprive them by encouraging your plants to grow and compete for the nutrients.
Look after your plants and most of the time they will deal with the algae.
Finally be patient.
If you find what caused it you can hopefully avoid repeating the same mistake. Sometimes green water will simply clear itself leaving you wondering what happened.
