DEFINE - What is Green Spot Algae (GSA)?
Green spot algae, also know GSA, start off looking like little small dots. Over time the dots will expand into larger dots, and can even combined with other green dots nearby. If left unattended to, it will run wild taking over your glass and entire leaves on a plant. It seems like slower growing plants are more affected than faster growing stems.
General causes:
Low phosphates to nitrate levels
Too much light
Stressed plants, slow growing, or old growth coupled with the above
REMOVAL - How to remove Green Spot Algae
The methods we are about to mention will not prevent GSA from coming back. We'll address that shortly. But here are a few ways to remove it from the tank.
Bleach dip - There is very little that can survive a cleach dip. Mix 1 part bleach to 20 parts of luke warm water. Sensitive plants, like crypts, dip fro no longer than 90 seconds. Heartier plants like anubias can be dipped for 150 seconds. Do no dip mosses and rinse REALLY well with dechlorinated water after the dip session. It won't totally dissolve the GSA, but will soften it for scarping.
Get scraping! - To get it off your glass/acrylic tanks, or plants leafs, you've gotta start scraping. Make sure to use a glass or acrylic saft scrub pad. You can even use the glass/acrylic scrub pad to rub it off beefier leaves, like of an anubias. But don't be too aggressive as you can damage the leaf.
Note: If you can not use options 1 and 2, you may need to trim the affected areas until its gone. Once you've taken all the preventative measures in the next topic, it should stop coming back.
Solutions - How to keep Green Spot algae from coming back
I am going to say this in every algae article... we need to make changes to how we've designed our aquarium otherwise the algae will just keep coming back. The definition of crazy is: doing the same thing over and over, yet expecting different results. Do not rely on fish, algae eaters, snails, shrimp etc., to fix the design flaw that we've introduced into our tanks.
Solution 1: The most common reason we see GSA is due to low or depleted phosphates. Plants absorbing nutrients is generally the cause in a planted tank. Now from what we know with Liebig's Law of the Minimum, we can't just dose phosphates from a Seachem bottle. We need to ensure that all nutrients is available at all times in proper ratios. So, we need to increase our fertilizations table as a whole. Check your phosphate levels and make sure they are in a 1:10 ratio with nitrates. Meaning, 1ppm of phosphate to 10ppms of nitrates. This is referred to as the Redfield ratio. When phosphates fall lower than the redfield ratio, GSA like to show up. Use a API's phosphate test kit to check where your phosphates are at, and dose something like Thrive All In One to bring not only your phosphates back up, but the entire fertilization table. For those more advanced hobbyists, we'd suggest looking into the EI method. You can view our EI Method video here!
Note: Once you bring up your phosphate levels with a holistic fertilizer, you'll need to manually remove all the GSA. Proper fertilization levels will prevent the algae, and not dissolve it. So get to cleaning!
Solution 2: Rethink your design. If you notice, GSA will develop on slower growing plants like epiphytes (anubias, buce, java fern). If you put a low growing plant under high light, you're bound to get some GSA over time. Focus on putting fast growing plants under high PAR areas of the tank, and tuck slower growing plants into corners and more shaded areas.
Solution 3: Focus on overall plant health. We are going to say this whenever addressing algae because happy plants fend off algae. When plants are happy they produce allelochemicals which are a defense mechanism for agale. But they can only produce this chemicals defense mechanism when thriving. As they say, an ounce or prevention is worth a pound of cure. If you are not currently running the ASG method, we would highly encourage you to do so. In the ASG method we teach you to:
Lighting: Have your light on a timer for 6-8 hours and ensure its outputting 80 PAR for non CO2 injected tanks, and 120 PAR for CO2 injected tanks. Learn all about PAR in this video. Reducing the PAR for a week or two can help reduce the excitement of algae.
CO2: Ensure your PH drops one full point before your lights come on, and stays there for the duration of the photo period. You can check your PH with an API PH test kit. Learn all about the PH drop method in this video.
Nutrients: Combined an aquasoil with a holistic fertilization method, like Thrive all in one, or the EI Method. Since aquasoils have a high CEC, they will absorb the nutrients from the water column and feed it to root feeding plants. This is the most efficient way of providing nutrients for both root feeders AND water column plants like mosses and floaters. Learn all about providing nutrients in this video.
Water chemistry: Main a GH/KH of 4, unless livestock dictate otherwise. Example, neocaridina shrimp like harder waters as in a GH of 8-12, and a KH of 2-6. Let your livestock dictate the GH/KH. Your PH will be what it is. Learn how to properly adjust your GH/KH/PH in this video
Filtration: Ensure your filter is able to turnover your entire water volume 10x an hour. Also ensure your have dedicated mechanical and biological filtration, and they are separate from eachother. Sponge filters just don't cut it. Learn how to properly set up your filtration in this video.
Husbandry: Once a week we should be processing a 50% water change. 75% water change when dealing with an algae issue until we can get things back under control. Remove 10% of the water to avoid splashing when cleaning surfaces. At this time you can scrape the glass/hardscape down THEN remove the rest of the water. This remove the algae we just scraped as we don't want it settling back into the tank if we can avoid it. Also make sure to kick up and remove any detritus from the corners or hard to reach places in our tank. Rotting organic matter in the tank can just cause unnecessary ammonia spikes which can lead to other alages.
If you are new to the ASG method, check out our Part 1 series on YouTube here! We cover all the topics above in more detail.
