I had an out break of red algae in my tanks.
Disclaimer: I rarely test my tanks. I do 15-20% water change once-twice per month, kalk in my top off, set and forget. It has been working for me for the last 3 years, so im continuing to do it. If you asked what my nitrate/phos/alk/ph levels are, i have no idea. I just use my eye to tell if something is off.
Having said that, last year my husbandry slipped and developed red slime algae. I used air hose to vacuum it up every night and did small water change to replenish the water I vacuumed out. Then on the weekend, I would do a 10-15% water change. After about 3-4 weeks, I stopped vacuuming every night. after about 6 weeks, I went back to my normal water change schedule.
hope this helps.