Please Help! How do I get rid of green floating algae?

[OU_Pilot]

Hey all,

At the start of the year I bought a 4g nano tank by Finnex. I had it set up with substrate and liverock within about a week and let it cycle for about 4-5 weeks before adding a small damsel and a few hermit crabs to help further the cycling process. For the first few weeks after I added the damsel the tank was crystal clear and I was doing 15-20% water changes every 12 days or so. Over the last 2 weeks though, it looks like green free-floating algae has taken over. I have pictures of my tank when it was clear and when the problem started to happen and the problem now. By now the tank is almost opaque and I can barely see my liverock. I am not sure how this happened. I did not add anything else to my tank, it just kinda happened. I have some chemi-pure elite on order....PLEASE HELP! THANKS!

4gallon Nano Reef by Finnex
30gph standard filter with activated carbon filters
Water temp. 78F
Nitrates flux between 0ppm after a water change and 3ppm 8 days after water change

[NvyroMental]

I was consider your feeding/lighting habits. Are you overfeeding? How long do you keep your lights on? By reducing both and performing several water changes more frequently, you should see a decrease in algae production. Remember that EXCESS nutrients and light are the key components to algae growth. Replacing your carbon filter couldnt hurt either. Hope this helps!

[Reefmedic79]

Are you using Lava rock for LR? Where are you getting your source water?

[Ostara]

Since you have no corals, just keep your lights off for three or four days. That will kill it off pretty quickly; I had this happen in my 40 gallon quarantine a few months ago. You could also do a water change to help dilute it. In only a four gallon tank you could easily change out 3 or 3.5 gallons if you wanted to.

As for a cause, mine was due to being lazy with water changes and after the lights out period I simply got my butt in gear maintenance wise and it hasn't reoccurred. I would recommend upping your water changes anyway; a lot of people I see with picos seem to change water at least once a week. I think a gallon a week would be good. An excessively long photoperiod could also be causing or attributing to the problem, so you can try cutting your lights back if you feel this could be an issue. The carbon is likely a factor if it came in a prepackaged filter insert. The carbon used in these is usually low quality and can leech phosphates into your tank. I would get the carbon out and replace it with the Chemi-pure when it arrives. Good luck!

[OU_Pilot]

Nvyro: I feed once a day, if that. My lights are usually on for about 15 hours a day. I have a timer, but I usually just turn it on when I wake up and off when I go to bed. I just replaced my carbon filter a few days ago, but it hasn't really helped.

ReefMedic: I am using liverock not lava rock. And I use RO water by the gallon from the grocery store and my salt source is instant ocean.

Ostara: Thanks for replying!. I will probably leave the light off for a few days. As for the water changes... aren't nano's/pico's much more sensitive to any water change? There is much less room for error, am I correct? Will a gallon a week really not damage my system? Again, I am relatively new to reefkeeping, and more so to nano's, so I appreciate your help.

[nlgill13]

15 hours is probably to long for you lights to be on (unless your trying to make your tank into a refugium). Just in retrospect, clams (which need some of the most light) thrive off of about 10hrs of light per day...Try somewhere between 8 and 10

Does your tank get direct sunlight during the day?

[lambchops]

I would start with a complete black out for a few days, followed by a water change, and I would dial back the 15 hours to around 8 personally. Have you ever tested the water that you get from the grocery store?

[Ostara]

Ouch, yeah 15 hours is far too long. I'd cut it back to eight or even less until you get the phytoplankton bloom under control.

All reef systems are sensitive to change if it is done incorrectly or too quickly. The saying about nanos and picos is that change happens quickly because it is a small volume of water, which is why many people opt for weekly water changes and maintenance. As long as you match temperature and salinity you can do water changes as much as you'd like. In fact if you wanted to do a 100% water change to get rid of the phyto and then cut your lights back, you certainly could. I believe another member that was experiencing this in a 10 gallon tank was considering doing that to cut it back quickly. I've even met people that routinely do 100% water changes on pico reefs because they feel it is the best way to keep nutrients from accumulating in such a small volume. Since you have no corals and only a damsel, even if you botched the parameters a little I think you'd be fine.

I'd feel comfortable doing that especially in a tank without corals, but I know it's daunting to many reefers. :lol2: If you're not in a hurry to get rid of it right away and that is too extreme, I'd do at least a 25% change to dilute it some (50% would be even better) and then leave it dark for three days, followed by cutting the lights back to 8 hours a day. That should get rid of it just fine.

I didn't mention it before because of tank size, but a UV sterilizer will also clear up a phytoplankton bloom if you happen to have a tiny one or one that can be crammed into a four gallon tank. I don't think I've seen one that small, but I wanted to cover all solution bases just in case. ;)

Keep us posted on how the de-greening goes! :)

[bnumair]

complete blackout for 4 days then cut ur lighting to max 6-8 hrs a day.

[OU_Pilot]

Thanks guys. Blackout in progress. Will let you know how it goes.

[Breadman03]

Just wanted to chime in here. I used the search function for the same issue. Time for lights out.

[fishgate]

UV Filter. by tomorrow the tank will be clear. 100% chance.

[sucker_fish]

filter floss, carbon, lights out for a few days and uv inline before skimmer and you will be crystal clear again