Algae problem in my 125
Hello everyone and thank you for allowing me to join your community. I am new to Freshwater Plant aquariums. Ive been keeping freshwater fishes for years now and have recently stepped up and decided to do the live plants thing too. Here is what I have and if I miss something please let me know. I have a standard 125gal (72x18x21). It has 2" of Black Flourite plant substrate and is being heated by 2 250w Aqueon Pro Heaters set at 78f. Lighting is provided by a 72" AquaticLife 12 lamp t5ho fixture for 10hrs a day, and the tank is filtered by a single Fluval Fx5 canister filter. This tank has been running since Oct 2012 but with stock lighting until Xmas when I purchased the AquaticLife fixture. Its stocked with 3 Lemon Tetras, 3 Pristella Tetras, 3 Congo Tetras, 3Kkhuli Loaches, 3 German Blue Rams, 4 Flagfish, 6 Sterba Catfish, 6 Rummy Nose Tetras and 6 Blue Tetras. All but the last 2 were originally housed in my 55gal until the new 125 cycled. All water perameters are fine according to the API Freshwater test kit. Ive also tested for Phosphate...zero. Im pretty confident the lights are the ultimate culprit because before the new lights, everything was fine. Now let me go more into detail about the light fixture itself. The 72" fixture was sold (without the option of changing lamps to Freshwater Plants) setup as Reef. It came factory with the following 6 lamps on each side, 1-10,000k 1-460/620 purple, and 4-420/460 Actinic lamps. I was only able to afford to relamp one side due to the cost of removing brand new lamps to replace with brand new lamps.... so I relamped the left side of my tank with 3-10,000k lamps and 3-6500k. I also planted the plants specifically on this side to see how they would do before I went all out buying plants. Im sure I have something messed up on my end with the lights but Im lost. I left the right side of the fixture with the factory supplied lamps. As it is I have to clean the glass every 4 days. Green algae grows rampid in here and I desperatly want to get things corrected. Any and all help is greatly appreciated. Thank you in advance, Jerome
I forgot to add that I only have about 8 Melon Swords in the tank and Im not adding any type of fertilizer or Co2
Is the algae growing more noticeably on either side of the tank? Also, you don't have to completely change out all of the actinic lights. Plants are able to photosynthesize in the wavelength produced by those bulbs, and can even help to turn certain plants red. I would suggest evening out both sides of the fixture between white and blue bulbs, and get more plants for the other side of the tank.
Having said that, it sounds like you simply have WAY too much light over your tank right now. Does your fixture have multiple switches so that you can turn off half the bulbs on each side? You really shouldn't be running so much light with so few plants. If you are able to reduce the number of bulbs being used, then that should really cut down on algae growth. Injecting CO2 and/or dosing excel (or other source of glut) with also help to keep algae at bay by promoting plant growth (in addition to being a liquid carbon source, glut also acts as an algaecide so it'll help to directly kill off algae).
I agree that there is simply too much light intensity, and this is the main cause of the algae. However, I do not agree that the light spectrum is going to work, but as this is connected with the intensity I'll deal with both together.
First, to explain something, since you say you are new to planted tanks. Aquatic plants need light that is of sufficient intensity plus 17 nutrients in order to grow; plants grow by photosynthesis. Plants will only photosynthesize fully if the light intensity is sufficient and all the nutrients are available. As soon as any nutrient is insufficient, photosynthesis will slow and depending upon the nutrient and just how much there is of it, photosynthesis may stop completely. This is referred to as the law of minimum, or the limiting factor to plant growth. Once this occurs, algae is quick to take advantage of the light and will begin to take over. So the aim is to balance the light intensity and duration with the nutrients; keeping this in balance provides the best environment for plant growth while keeping algae at the disadvantage because plants will out-compete algae if everything is available to them.
The fact that things were "better" with the old light supports the above. With less light intensity, the plants were able to photosynthesize to some degree using the available nutrients. But as soon as you increased the light intensity, and significantly, but did not increase the nutrients--plants are at a big disadvantage and algae is increasing.
So, the solution. Decrease the light intensity (duration also plays into this, but the actual intensity is more significant) and increase the nutrients. Echinodorus (sword plants) are heavy feeders, and it is not likely they will find sufficient nutrients from just natural sources to last long.
Light. You have T5 fixture, so only T5 tubes will work. As was asked previously, can you operate half the lights without the other half? If so, this will help. Next, I would only use the 6500K tubes. Unlike the previous poster, I do not believe plants will do as well under actinic and blue light alone. Plants need red and blue light, and more red than blue in fact. And scientific studies have proven that plants grow best under light having a kelvin between 6000K and 7000K. It is possible to create a mix of daylight (as we generally call the 6500K light) and cooler (the higher K number indicates cooler light, more blue and less red in the spectrum), but I would not use actinic tubes for this. I had good plant response in my 5-foot tank from one 6700K tube and one 11000K tube, and the natural light was a bit crisper (cooler white) which I liked. But you're dealing with T5 and probably HO (high output) so you are going to have to lessen the number of tubes somehow.
Nutrients. A complete fertilizer is going to be essential with this light, even after you reduce it. You don't need to mess with CO2 diffusion, I never have, and you can see the results in my tanks, one is pictured below for example. This happens to be my 5-foot 115g which is lit with two 48-inch T8 tubes, both 6500K. I dose Flourish Comprehensive Supplement twice a week, and I have one Flourish Tab next to each of the five large sword plants, replaced every three months. This balances the light which is on for 8 hours daily. Any more light duration and I begin to see brush algae increasing; all about balance again.;-)
Hope this helps; don't hesitate to ask questions. A fuller background to a natural or low-tech method is set out in my 4-part series "A Basic Approach to the Natural Planted Aquarium" sticked at the head of this section of the forum.
I would be interested in any scientifically-valid studies on light spectrum, as the only ones I have so far come across did prove that light between 6000K and 7000K with all else being equal caused the fastest rate of photosynthesis in aquatic plants in aquaria.
I've read several cases of blue-only lights being used in planted aquaria with great success (I wouldn't do this myself simply because I wouldn't find it appeasing to the eyes). I've also read where blue lights were added to previously white-only fixtures and improvement was shown in growth rates, blooming, coloration, and pearling. I've personally grown corals under just blue LEDs over the course of a couple months, and mainly use the the mix of whites and blues that I currently use in my DIY fixture in order to obtain the most aesthetic color temp for me. If plants can't grow under blue light, then the chlorophyll pigments wouldn't peak at all in the blue spectrum. For example, the chloryphyll-a pigment peaks at around 435nm, chlorophyll-b around 470nm, and the combined photosynthesis of all pigments peaks at about 425nm (even higher than the peak in the warm spectrum).
Which may explain the improvement with the blue added to daylight. Increasing the light intensity and penetration would likely be of some benefit, depending what was over the plants before this. This likely explains why my plants were fine under the mix; though to be honest they are no worse under the sole 6500K spectrum, so from my experience this is not significant [this also supports what will follow below]. These other situations may have variables that we know nothing of, which is why I referenced scientifically-valid tests. Only in such controlled situations can one draw reasonably accurate conclusions when we are looking for significant difference.
The controlled tests that determined the best light to be a mix of full spectrum and cool white, which is generally accepted to be in the 6500K range, are from 1987 [K.Richards, "The Effects of Different Spectrum Fluorescent Bulbs on the Photosynthesis of Aquatic Plants," Freshwater and Marine Aquarium, July 1987, pp. 16-20, cited in D. Walstad, Ecology of Aquarium Plants, chapter XI]. Every planted tank source I have so far come across has suggested that daylight tubes between 5000K and 7000K provide the best light, and some of these people are professional botanists.
I was just re-reading Walstad when looking up the Richards reference, and came across these two paragraphs [pp. 180-181] in which Diana is commenting on the results of the study:
The fact that plants did very well with Cool-white, which produces mostly green-yellow light was an unexpected result of this study. One would have expected the plants to do better with Vita-Lite [this was the "full spectrum" tube used in the study]. This is because Vita-Light was designed for growing plants; its spectrum, which is rich in red and blue light, matches the light absorption of plant chlorophyll much better than Cool-white and many other fluorescent bulbs.Here again we have the 6500K "daylight" mix that all agree works so well; red, blue and green-yellow.
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