Dreaded Algae

[Mike Steed]

Hi. I hope someone can help me. I have just set up a 250 litre (50 gallon) planted tank. Measurements are 110mmx50mmx50mm. I have used Oliver Knott Nature soil and filled the tank with RO water. Lighting was 4x 39watt T5 tubes lighting the aquarium for 6 hours. I was unable to get a pH reading above 5.3 so carried out 2 water changes of 30% using Tapwater. The pH rises after the water changes but has since dropped back to 5.8 and KH is less than 1 degree. I have now noticed algae starting to grow on the rocks and some of the plant leaves. I have reduced the lighting to 2x 39 watt T5 tubes for 4 hours. Phosphate reading is zero. I would be grateful if someone could advise me why the algae has started to grow and how to get rid of it. Also, have I done the right thing in reducing the lighting to 2 tubes. Many Thanks.

 

[Teephphah]

I'm just a newb around here, but I'm pretty sure the experts are going to tell you that you need to do something with CO2. The general concensus is that algae pops up when your CO2 levels are either too low or when they're fluctuating. Stabilize the CO2 and you should be good.

They (the experts around here) will probably recommend dosing with some sort of liquid carbon (Flourish Excel, for example) in the short term, with some sort of gaseous CO2 injection as the long term solution.

But again, I'm no expert, that's just my hunch as to what the grown-ups will tell you.

 

[lljdma06]

Hi. I hope someone can help me. I have just set up a 250 litre (50 gallon) planted tank. Measurements are 110mmx50mmx50mm. I have used Oliver Knott Nature soil and filled the tank with RO water. Lighting was 4x 39watt T5 tubes lighting the aquarium for 6 hours. I was unable to get a pH reading above 5.3 so carried out 2 water changes of 30% using Tapwater. The pH rises after the water changes but has since dropped back to 5.8 and KH is less than 1 degree. I have now noticed algae starting to grow on the rocks and some of the plant leaves. I have reduced the lighting to 2x 39 watt T5 tubes for 4 hours. Phosphate reading is zero. I would be grateful if someone could advise me why the algae has started to grow and how to get rid of it. Also, have I done the right thing in reducing the lighting to 2 tubes. Many Thanks.

Well, reducing it to 2 tubes was certainly a step in the right direction, as was the reduction of the photoperiod. This lighting level, however, will still require some sort of CO2 method, whether it's gas injection or liquid dosing. What are you trying to grow? If they are not hard plants, I'd say reduce it further to just a single T5 tube.

 

[Mike Steed]

Thanks for the advice. I'm sorry but I forgot to mention in the post that I am injecting CO2 which is controlled by a pH meter, but as the pH at the moment is low, I am having to keep adjusting the meter as the pH falls. I am presently growing Staurogyne sp; Rotala rotundifolia; Hygrophila Polysperma; Pogostemon Stellata and Hemianthus Micranthemoides. All the plants seem to be growing but then the Algae strikes!!

 

[RadaR]

0 Phoshpates. That's not great to start with. Plants need phosphates, and phosphates don't cause algae either.

I am injecting CO2 which is controlled by a pH meter,

There we go. Here's the problem. Your Co2 is switching off when the pH drops to a certain point because it is assuming the pH drop is solely down to carbonic acid formed when CO2 dissolves in water. It's assuming this low pH means high CO2 which could be dangerous. When infact other thing influence the Co2, such as your substrate.. You're probably not getting enough Co2 because it's switching off too early.

 

[Mike Steed]

Thanks for the advice. Seems I'd be better off switching the CO2 with the lighting. Cheers.