Help with Ongoing Algae Bloom


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Hello, I have a 55g, one year old tank running on a cascade 700 +aquaclear 50 filter. Gravel substrate, plants include anubias and java fern. 2 swords, 9 ember tetras, 7 ruby tetras, 1 clown pleco and 1 rubbernose pleco. I have had a mild algae bloom for months. I have tried treating with a clearing agent (Nutrafin Clear Fast) and filter floss on my intake, and it clears for a day or less, and then back to cloudy. I have a nicrew classic blue and white led light. I have now tried adding ferts using NilocGThriveC - just added them once a few days ago. I am truly at a loss and starting to feel discouraged. I had a major bloom when I was first setting up the tank and got rid of it with a blackout for a week, but this one is not as severe, but just chronic. I have no visible algae growing on my glass or plants. I have been doing 20 percent or so water change weekly. Any advice?


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Forest City Ontario
More than 10 years
Reduce light intensity if possible.

Reduce photoperiod to 5 hours per day max (until algae has subsided, then slowly increase back up to 8 hours per day over a few weeks).

Ensure you are providing adequate nutrients for the plants (unhealthy plants promote algae).

Dose Flourish Excel or equivalent Met14 at the “after water change” rate on the Excel bottle once per day.

Manually remove all algae you can.

Manually remove excess organics in the tank by gravel vacuuming and cleaning filter media in old tank water every water change.

Manually remove any decaying or dead plant matter.

Increase water change frequency, and the amount of water changed.

Consider spot treating badly affected areas or dipping plants / hardscape in a Flourish Excel, Met14 or H2O2 + water solution. Google search which method you think would work well, and for general ratios to mix a safe solution. Certain plants can’t tolerate these chemicals, so ensure you do a little research prior to dipping / spot treating plants.

If using CO2, ensure CO2 is dropping the pH of the tank water a full 1.0 – 1.2. To do this, measure the pH of tank water with no CO2 dissolved in it, and then measure again 2-3 hours after CO2 has been running. Ensure the drop in pH is a full 1.0-1.2. If the drop is not there yet, slowly up CO2 over a few weeks until at least a 1.0 drop is achieved, and watch fish / livestock carefully. Adjust CO2 down if you notice fish gasping at the surface and consider running an airstone at night when pushing a 1.2 or greater drop. For example, a tank water pH of 7.5 with no CO2 dissolved in it, should reach a pH of 6.5 – 6.3 for CO2 to really shine, and for maximum plant health.

Consistency in CO2 levels is key to plant health. Keep CO2 levels as stable as possible once a desirable level has been reached.

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