Hi Kai,
that depends on what your planning to do. But to start with: I am not an expert by any meanings. I read a lot and get really much information out of that. Diatoms and hair algae were problems in my current tank, i defeated both (ok, guess diatoms defeat themself
).
Please do not start to fight one thing after another. If you fight the hair algae issue and do nothing else, you will get into the spot I found myself in. Namely: Green Spot Algae. Instead I will try to give you a short overfew, but I guess you have to use the searchengine of your choice to find further information.
Since your algae (talking the hair algae) is most likely related to pure nutrient availability, I would stay back from adding fish until you fixed it. I would recommend chosing a appropriate dosing routine. My suggestions are most of the time (don't know your tank, hence a bit cautious) the following:
High-Tech-Tanks (0,6 Watts per Liter / 40 Lumens per Liter and more + good CO2)
Look at the
EI Dosing Method. It is simple and works most of the time.
Lower-Tech-Tanks (anything below the values above)
PPS Pro is a good approach. I have never tested it for myself but I never heard anything bad except some minor GSA (Green Spot Algae) issues, which can be handled with a bit more PO4 Dosing. Another posibility would be the
Lean EI Dosing. Both systems are pretty simple and work for a lot of people.
My current tank is running well, using the EI Dosing Method in a bit reduced way. Kind of a mixture of EI and Lean EI Dosing. I would suggest reading
this post by Tom Barr, who came up with those routines. There he explains how the EI system may be adapted to tanks for less water changes (aka Lean EI Dosing). I think it is more than just that. It makes the system easier for beginners, because classic EI is something like driving a sports car (stolen from scapefu podcast, but simply true): It's much fun as long as everything works out great. But a brief moment of distraction and there are major problems.
To wrap things up, I have three questions for you:
1. Are you running a CO2 system?
2. What fertilizers are you using and how much do you add?
3. What kind of substrate do you use? Basic gravel, Sand, ADA Soil or even anything else?