[Ms_Maloney]

Hi all, hoping for some advice on some algae that has gotten a foothold in my aquarium. First off, I am a beginner. I went feet-first to a dirted, heavily planted tank after reading (to the best of my non-technical ability) Ecology of the Planted Aquarium (hi Diana thank you, if you read this!)

I have a 20gal long that's been up for a year. It's lightly stocked with Celestial Pearl Danios, neocardinia, and pond snails. Plants are mostly fast growing stems—rotala, water wisteria, pogostemon, vallisneria. And some water lettuce, crypts, monte carlo, and dwarf hairgrass. Substrate is organic potting soil capped with small gravel, and I keep a small sponge filter in there that I sometimes run.

Once I got it balanced within the first month or two, it's been amazing. Plant growth has been bonkers, fish and shrimp doing well—I now have CPDs and shrimp of all ages, they're so fun to watch!

The challenge came about 3 months ago when we bought a new home and moved across town. Amidst the chaos, I've lost the lovely balance that I had for so long! About 6-8 weeks ago the tank got completely overrun with green hair algae and green water. I've been trying to beat it back with manual removal, water changes, and a weeklong blackout. During this time, plant growth slowed as well. Maybe photosynthesizing had slowed due to the heavy algae? (it was embarrassingly bad)

I use a siesta in my lighting schedule: 3 on, 2 off, 5 on. The new location for the tank is right next to a window, so I thought maybe my siesta is being negated by the sunlight (indirect but bright, north-facing). Then I read last night in Diana's book that sunlight doesn't seem to reduce CO2 rebound during siesta, AND that algae are basically shade-loving plants that can't necessarily make use of stronger light like fast-growing aquatic plants can.

So, maybe I've just gotten myself turned around a little and need to be straightened out—but I'm observing 3 things and trying to suss out the where the cause/effect relationships actually are.

1. More light on the tank, due to the new location
2. Reduced plant growth, due to . . . less photosynthesis? Or depleted nutrients in substrate?
3. Lots of algae, due to . . . excess light? Or excess nutrients in the water column?

Is it possible that my plant growth slowdown was actually the CAUSE of the algae, not a side effect of reduced photosynthesis during the heavy algae? Is my substrate depleted, leaving the tank vulnerable to algae from free-floating nutrients in the water column? It's also possible that I over-pruned at one point (I've since added more plants).

Essentially, I'm hoping to get some strategies for troubleshooting my issues. My first tack was to reduce light, so I did the blackout and then increased my siesta to 2 on, 4 off, 4 on but that seemed to hinder plant growth even more . . . so I wonder if I over-corrected and need to actually boost lighting back up to support the stem plants' growth?

Would love anyone's thoughts on how to troubleshoot. Thank you so much, this forum has been invaluable to a learner/lurker like me

 

[maico996]

You might try decreasing the intensity of the light, not the duration. Also, if you have an LED light with control over color spectrum, try reducing the blue lights. I run mine at 5% and my algae problem has decreased significantly. It's not gone, but much better than before. You can also try putting something over the back glass to help keep the sunlight out of the tank. Also, your photo period is only 6 hours of lights on and I think Diana recommends 10 hours if I remember correctly? Six hours is probably not enough time for good plant growth.

 

[Michael]

Agree with all of malco's comments. Are the photos current, with algae? If so, the tank looks great and you don't have a major problem.

I doubt that your substrate is "depleted". Remember, soil substrates are active systems, absorbing nutrients from the water when abundant then releasing nutrients to hungry plant roots.

In my experience it is more difficult to manage tanks that receive a lot of natural light. You don't have as much control over light intensity and photoperiod, especially as seasons change. Try duplicating the tank conditions in your old home at your new home.

 

[erose]

Off topic, but I love your fish, such cute photos! I hope to start a CPD tank in my next place. How do they do with shrimp? Are the shrimp still able to reproduce or are the shrimplets typically culled by the fish?

 

[dwalstad]

Quote: The challenge came about 3 months ago when we bought a new home and moved across town. Amidst the chaos, I've lost the lovely balance that I had for so long! About 6-8 weeks ago the tank got completely overrun with green hair algae and green water. I've been trying to beat it back with manual removal, water changes, and a weeklong blackout. During this time, plant growth slowed as well. Maybe photosynthesizing had slowed due to the heavy algae? (it was embarrassingly bad)

So many variables! A week long blackout could truly harm plants. I have never recommended blackouts for algae control. If plants can't photosynthesize, how can they keep their roots safely oxygenated? Blackouts harm plants more than algae.

Floating plants, manual removal of algae, and UV sterilizers (for Green Water Algae) are effective methods that target algae not plants.

In planted aquaria, plants and algae are always competing!

 

[Ms_Maloney]

You might try decreasing the intensity of the light, not the duration.

Thank you for the feedback, maico! I will try reducing intensity, and knocking blue down. I'm setting to 70% intensity overall (except blue, that's at 5%) and going back to 10hr duration with 2 siesta. I'll let you know how it pans out.

Are the photos current, with algae? If so, the tank looks great and you don't have a major problem.

Michael, thank you for your input. I appreciate it! Yeah, these photos are current—after lots of manual algae removal. Hopefully I can take measures to keep it looking like this. I also tossed in two pothos cuttings to soak up any free nutrients, we'll see if that helps . . . thanks again.

In planted aquaria, plants and algae are always competing!

Diana, thank you so much for your reply. What a pleasure to get your thoughts on my tank I'll consider a UV sterilizer, I was re-reading your section on that the other night and think that may be a good idea.

Clearly my head's spinning a bit with the variables! But the feedback that a blackout wasn't a great idea is helpful—that solidifies a path forward for me. Plant growth has started again in the last couple days, and I am hopeful that manual removal and focusing on plant growth will be my way back to balance. In summary, here's my plan:

• Reduce intensity of Red, Green, White to 70%, and reduce Blue to 5% — all were 100% previously
• Reset photoperiod to 10 hrs/day w/2 hr siesta (5on, 2off, 5on) — previously I had reduced light to ~6hr to try accounting for bright window location
• Continue manual algae removal, consider UV filter
• Also added 2 pothos cuttings to the existing floating plants to absorb excess nutrients

Thank you all for your feedback, I'll keep you posted!!!

 

[Ms_Maloney]

Off topic, but I love your fish, such cute photos! I hope to start a CPD tank in my next place. How do they do with shrimp? Are the shrimp still able to reproduce or are the shrimplets typically culled by the fish?

Hi erose, thank you!! The CPDs are so much fun, and I've been super happy that they've been spawning!

The shrimp are doing well, though I don't heat the tank so reproduction has not been super fast. And, I think the fact that we moved house right when the weather starting warming up kinda put a pause on breeding too. That said, I've had shrimplets grow up in this taknk with the CPDs for sure. The CPDs are really very small and there's enough plant coverage, I think, to allow both shrimplets and CPD fry to grow up

 

[Cawafuoshi]

Not running a Walstad tank but have been digging lots of literature from the 80s, 90s up to the early 2000s just recently. Everywhere they recommend 12-14 hours periods. My first tank ever in 1993 I ran lights for 12 hours daily, no ferts, no CO2, heavy stocking but plants did pretty well and no major algae issues. No fish died prematurely.

My experimental 5G and 14G started to have algae issues (green hair algae) and reducing photo periods did not help at all. What helped was more ferts and CO2.

Currently running a 20L on a 12 hours schedule 2*6 hrs with a 4hrs siesta, ferts, CO2, no noticeable algae but some spots on the glass.

 

[dwalstad]

Not running a Walstad tank but have been digging lots of literature from the 80s, 90s up to the early 2000s just recently. Everywhere they recommend 12-14 hours periods. My first tank ever in 1993 I ran lights for 12 hours daily, no ferts, no CO2, heavy stocking but plants did pretty well and no major algae issues. No fish died prematurely.

My experimental 5G and 14G started to have algae issues (green hair algae) and reducing photo periods did not help at all. What helped was more ferts and CO2.

Currently running a 20L on a 12 hours schedule 2*6 hrs with a 4hrs siesta, ferts, CO2, no noticeable algae but some spots on the glass.

Thank you for the input. Valuable feedback, as I see so many people recommending 8-9 hour photoperiods to control algae. It obscures the fact that most aquarium plants require a photoperiod of 12-14 hours/day. To control algae, it is much smarter to introduce a midday Siesta than to reduce the photoperiod. That way, you are not inhibiting plant growth.

 

[Batjok]

The aquarium does not need a lot of light - turn on the light in the evening when you are at home.
If you want to give the plants a lot of light, then put the aquarium near the window.
You don't have to turn on the lights during the day.
Only a good filter will save the aquarium from algae.

 

[johnwesley0]

The aquarium does not need a lot of light - turn on the light in the evening when you are at home.
If you want to give the plants a lot of light, then put the aquarium near the window.
You don't have to turn on the lights during the day.
Only a good filter will save the aquarium from algae.

I suspect "guppy grass" in a window leaves a lot of room for experimentation.