Cyanobacteria Is Back, Please Help!

[keastclan]

and what type of size am I going for? 1000, 1500, higher? in a 180 litre bow fronted tank. Completely unrelated too should I reduce the hours my lights are on from 8 to say 6?

 

[KirkyArcher]

I've just got a maxijet power head/water pump to help with my water flow with a home made directional nozzle fitted, http/www.seapets.co.uk/products/aquarium-supplies/fish-tank-equipment/aquarium-filters/power-heads-and-water-pumps/maxijet-aquarium-water-pump-750.html Though to get easier flow direction a regular wave maker/circulation 1000l/h pump will suffice http/www.seapets.co.uk/products/aquarium-supplies/fish-tank-equipment/aquarium-filters/power-heads-and-water-pumps/fluval-sea-cp1-circulation-pump-1000lph.html though I think these are a little more intrusive visually, I think anything stronger than 1000 l/h will be needlessly overpowering in your 180l tank, and yes as I said earlier a reduction in lighting period will help immensely until you get on top of the situation

 

[DoubleDutch]

Isn't an idea to check on nitrates first (before adding) and phosfates as well?

 

[Meeresstille]

Have you checked if your filter is the right one for the size tank you have? 
 
Another option would be to add another filter. For example my tank is a 40 gallon long (150 liter, 122 cm long) and each filter is good for 50 gallon. By running two filters on opposite ends of the tank there are no dead spots, and should one fail, there still would be the second one to provide some filtration! I can adjust the water-flow on each filter, which I like very much, since I do have species of fish that don't necessarily like big water flow!