T5 HO and algae

I want to share a personal experience with my tank. I know this is commonly known, but took me by surprise how quickly it happened.


So I have a 72" AquaticLife T5 HO and Lunar LED light fixture with eight, 36" T5 bulbs. The fixture can separately run blues (two 420/460nm blue bulbs and two 460/620nm purple bulbs), whites (two 10,000K white bulbs and two 420/460nm blue bulbs), and the 6 led lunar lights.


I had been running my blues for 10 hours a day, my whites for 5 hours a day in the middle of the blue period, and my lunars for 30 min following the end of the blue period. I had noticed about 3 weeks ago I was starting to get some nuisance algae (cyano) on my sand bed in specific areas that produced bubbles every day and in greater numbers as the towards the end of the daily lighting period. Well the bulbs were almost a year old and I knew they needed replaced. Trying to be conservative, I replaced 6 of the 8 bulbs, leaving the 11 month old 10,000K whites alone thinking they were ran half as long during this time and I could stretch them out a little longer. About a week ago, the 6 bulbs were replaced, yet my nuisance algae was getting worse and worse. So what I did was turn the white cycle off altogether and reduced the blue cycle from 10 hours to 8 hours. The next day the algae was still there but much fewer bubbles. And the next day, it was like the algae was not even there!


Without any other changes to the tank, I can only conclude that when my 10,000K bulbs start to go bad, they can cause chaos pretty quickly. Needless to say, I have two bulbs on their way.


Anyone else experience a similar situation?

 

That very well could be the issue as well. My thought process behind the bulbs is that my tank is just over 2 years old now, where practically all of my algae issues came in the first year of having the tank due to a combination of things from adding too fast to figuring out just what I needed to run my tank successfully.


I run about 200 grams of RowaPhos in a reactor and swap it out monthly, run a reef octo xs160 skimmer (i would have got a bigger one if money allowed at the time) and run pretty wet, light carbon use, about 140 lbs live rock. Tank size is 125 with a 30 gal sump. Pretty good water turnover with about 700-800 gal/h in water return and another 1150 gal/hour each from my wavemakers. I do 17 gallon water changes weekly and dose the tank with c-balance combo solution daily (I know there are easier and better ways, just comfortable right now with a two-part solution).


This last 12 months has been pretty nice as far as tank maintenance goes with very little issues. I do test nitrates every once in a while but my api test is not overly sophisticated, always shows yellow (0-5 ppm) and phosphates always between 0 to 0.25 ppm. My salinity is always kept at 1.025-1.026, Ca 440-480. Alk 10-11.


To be honest I haven't added much for bioload over the last 6 months. No new fish and a handful or corals but nothing recent. I have a red sea sailfin tang, yellow tang, 2 black/white clowns, blue throat trigger, 6 line wrasse, usual suspects in a clean up crew, and corals decently covering my live rock. Like I mentioned, this thing started about 3-4 weeks ago and slowly got worse and then over like a 3 day period, seriously just vanished. Now when I say it was bad it wasn't on my rocks, just a few spots on the sand and return pipes.

 

I use AquaticLife bulbs and never put much thought into cheating on the brand since it is the brand of my fixture.


I will report back what happens when the 10,000K bulbs are installed (in 5-9 business days..). I am a little worried that there may be a root cause to this other than the bulbs, but to be honest, for sometime now my tank has been pretty stable. My corals are growing pretty well (and sometimes multiplying in areas I prefer them not to be), but no real issues. I do have a flower pot coral I bought last April that is start to regress some, but that's another story.

 

On another note, I am interested to see what other T5 users are doing for their light periods. Some reef guys smarter than myself told me the 10 hours blue/5 hours white and blue. The led lunar lights are really pretty cool as well at the end of the day.


If I could start over again I would probably go led's, now paying for bulb replacements every 10-12 months with t5's!

 

I have done a 3 day blackout before during the first year of having my tank, and it did work wonders. It's in the basement, so "blackout" was not a problem.


As for the current situation, still no cyano popping back up. I have not replaced my 10,000 k lights yet, so therefore, have been running with no white cycle for the last few days. Corals have not been affected negatively by appearance or extension at least. If the cyano comes back on the sand when I install new lights and turn the whites back on, I will have a couple answers then.