Green spot algae
Green spot algae close up
Nothing has really dramatically changed in the Fireplace Aquarium but I feel the green spot algae has been growing back quicker than it used to. I was having to give the tank walls a credit-card scrapedown every three or four weeks, but now it seems up to every other week. I tried increasing the dose of liquid carbon (a.k.a algaecide) from 1.0 ml per day to 1.5 ml per day, without noticeable effect other than using up 50% more EasyCarbo. For sure though the hours of daylight are increasing rapidly now and even though the aquarium is 4m from the window, it is a south-facing window and bright all day long. I’ve reduced the lighting supplied by the Tuna Sun LED light by reducing the period of full intensity light in the aquarium daily lighting sequence by 2 hours per day, so we’ll see if that helps. I have long suspected that I’ve been providing more light than necessary so let’s give this a go. I’m also going to knock the liquid carbon dosing back down to the original 1.0 ml per day.
Aquarium daily lighting sequence
Revised Timing
Description
Previous timing
00:00 – 09:00
09:00 – 10:00
10:00 – 11:30
11:30 – 14:00
14:00 – 17:00
17:00 – 18:00
18:00 – 00:00
lights off
5% intensity, 0% colour
ramp up intensity and colour
70%* intensity, 80% colour
ramp down intensity and colour
5% intensity, 0% colour
lights off
00:00 – 09:00
09:00 – 10:00
10:00 – 10:30
10:30 – 15:00
15:00 – 17:00
17:00 – 18:00
18:00 – 00:00
Three week algae follow up
*The algae problem is better with nothing noticeable for the first two weeks after the change. On the third week a reasonably comprehensive scrub-down was in order, but not as bad as before. I am noticing spot algae on some of the recent Lobelia cardinalis ‘Dwarf’ leaves however, so I’m doing a further light reduction with max intensity reduced from 100% to 70%.
Green spot algae on Lobelia cardinalis ‘Dwarf’
The algae isn’t on the most recently grown leaves, but seems to be on those two or three layers down from the most recent leaves – those still in bright light but no longer actively growing. It’s the usual problem of the older leaves get colonised by the algae so I’m hoping reducing the maximum lighting intensity won’t impact the plant growth but will take the edge off the algal growth. I’ll provide a future update.
Reduced intensity lighting sorts out the algae problem
As a second follow-up, reducing the peak lighting intensity from 100% to 70% has been a really positive difference maker. The algae and I now have a much more comfortable relationship, where I give the walls of the tank a bit of a light scraping every 4-6 weeks and otherwise all is well. Lower leaves aren’t really being heavily colonised anymore. If you’re having green spot algae problems, give reducing the lighting intensity a try.