Plant tank problems - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 11 Old 02-03-2011, 11:17 PM Thread Starter
Plant tank problems

I have a 36 gallon bow front aquarium and a 75 gallon aquarium, both are planted tanks. I work at a pet shop and know quite a bit about aquariums but these problems ive been having, no one i know can help.

for the 36-
i have an aqueon filter, along with a magnum polisher i run a few times a week. I also have 2 t5 HO lamps, one 67K and one 10,000K, they are like 36 watts each. I use plant substrate, i believe it was flourite but it wasnt the red one its the black one. I have a couple of swords, some vals, and a few other plants but they never seem to grow, they are tall and lanky but never spread out. they are just stalks til about the top third of the tank and my melon sword never grows. it sprouts new leaves but they are BLACK and never grow.

for the 75-
its only been set up about 2 months now but i didnt have this problem with any other tank ive ever set up. Im using a marineland canister filter with a magnum polisher occasionally. I have a quad t5 HO light fixture, with 2 67ks, one 10,000k, and one colormax. Im pushing 200 watts on it. Ive been having a TERRIBLE red and green algae bloom. and all of my plants are getting the brown algae all over them and its killing them. all you can see is little oxygen bubbles floating off the plants.

What am i doing wrong? I dont have any CO2 systems right now, havent saved up that much money. I use flourish iron, potassium, and excel.
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colliesandconstrictors is offline  
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post #2 of 11 Old 02-03-2011, 11:35 PM
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Oh yuck, it's the dreaded cyanobacteria, also know as blue green algae. I myself am doing battle with this in my 100gl planted. None of my other tanks have this junk, which I have come to despise.
Before I suggest a method for correction, what fish are you housing in each of these tanks??
I also think you have way too much light on your 75gl. This could be a huge contributing factor to algae growth.
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post #3 of 11 Old 02-04-2011, 01:17 AM
You need more plants and less light for starters...

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post #4 of 11 Old 02-04-2011, 12:55 PM Thread Starter
in my 36, i have various tetras and a swordtail and some danios. in my 75, i have some baby angels and thats it.
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post #5 of 11 Old 02-04-2011, 02:41 PM
for the 75g, that amount of light w/o CO2 and additional ferts is perfect for algae of all kinds. I treated my cyano with maracyn, but its usually left as a last resort kind of deal, once u get BGA, its not something thats treatable by just turning lights down and removing wattage and whatnot. You need to do a blackout or dose meds and get rid of it. as well as keep a strict water-change schedule to get rid of the buildup of organics. Excel helps, but using iron and potassium doesnt give your plants the other nutrients they need. Instead of iron and potassium, use flourish comprehensive. I also read somewhere that excess iron can cause health issues for fish.

Also 10,000k light is for SW tanks, freshwater plants cant absorb past 6700k, any bulb stronger than that feeds algae with the excess light.
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post #6 of 11 Old 02-04-2011, 04:27 PM
Originally Posted by SinCrisis View Post
Also 10,000k light is for SW tanks, freshwater plants cant absorb past 6700k, any bulb stronger than that feeds algae with the excess light.
Not quite right. 10,000K MIGHT be more effective on SW then FW does not mean it has no place. I have seen lots of 10,000K bulbs used on FW. They are normally used in combination with a different bulb like the OP has them. Its not the 10,000K thats is causing the algae its just the quantity of light he has. I'm not sure where you got the idea that plants can't absorb past 6700K, but there is really no truth to that...

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post #7 of 11 Old 02-04-2011, 08:33 PM Thread Starter
so if i do a black out and treat with marycin it should get rid of it? how long should i keep the lights off and what are the chances of it killing my angels? should i move them to my other tank or is there a possibility of transfering it with thefish?

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post #8 of 11 Old 02-04-2011, 08:44 PM
that seems overkill to me. Either way if you don't cut back your light/ add more plants algae will just return when you are done with the black out. You might be able to run all your light eventually, however you need an established tank that is heavily planted and can uptake everything you are giving it. Currently you are running almost high tech minus CO2 with very few plants and wondering why you have algae. Your input does not match up with your tanks needs at all...

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post #9 of 11 Old 02-05-2011, 01:33 AM
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I agree with what's been said on the excess light and imbalance of nutrients and light (both together and the nutrient imbalance itself).

First, colliesandconstrictors, welcome to Tropical Fish Keeping forum.

Now to business. If any of what I say is already known, please just read on; it is to me crucial for one to understand the basics behind the process.

T5 HO light in my view is too intense for low-tech or natural systems, except perhaps as a single tube over some larger tanks. Plants require adequate light (spectrum, intensity and duration) plus available nutrients in balance. Plants grow by photosynthesis, and this will slow and even stop when something is missing. We call this the minimum factor. Light should always be the limiting factor, because while plants are quite specific in their requirements, algae is not and can utilize any and all light. As long as the plants are using the light, which means they have sufficient in balance with the nutrients to be photosynthesizing, algae is left out. As soon as the plants slow down, and the light remains, algae steps in. As you have seen.

For a low-tech or natural system in a 75 gallon tank, I would not go beyond two regular T8 tubes, or one T5 HO. Assuming in both cases 48-inch tubes over a 4-foot tank. This is all I have over my 4-foot 70g, 90g and even my 5-foot 115g, and I have very robust plant growth [and no added CO2]. I get algae even with this from time to time--it seems to be seasonal. But reducing the light always handles it.

I agree with SinCrisis on the fertilizers. You are adding a lot of a couple and none of the others that are essential. Plants need 17 nutrients, and they need them in proportion to each other, within reason. In a natural system, the best way to achieve this is a good comprehensive fertilizer like Flourish Comprehensive Supplement for the Planted Aquarium that SinCrisis mentioned. Same principle applies as with the light: when something is missing, plants can only fully photosynthesize to the point where that nutrient is no longer available, and algae jumps in.

Last comment on the light. [Mikaila and I agree to disagree on this.] Plants need red and blue to photosynthesize, there are scientific studies to prove this, and algae will be more likely to appear when the light is weighed on the blue side. I am sure it is not without reason that every planted tank author writes that actinic tubes do not promote good plant growth; I am not going to argue with all of them, some are botanists, some biologists, some microbiologists. Now, it must be said that other things can affect this, so it is not cut and dried; but every thing that is "slightly out" is just one more obstacle to the goal. I would use a combo of full spectrum and daylight, in other words tubes with a kelvin between 6000K and 7000K. All else being equal, plants do grow "stronger" under this light. They will grow under many other types of light too, to some extent. But again, in a low-tech or natural system, my advice is to keep things simple across the board. The more "natural" the light and nutrients, the less chance for trouble.

Last, I would not use antibiotics to cure an algae problem. I have done this, and nearly killed my plants. Some species of swords in particular are very intolerant of Maracyn and similar products. Clean up the tank, reduce the light, balance the nutrients, and things will settle down.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #10 of 11 Old 02-05-2011, 06:28 PM
[I know we always disagree on this]... but kelvin temp does not tell you color spectrum. Kelvin temp is the color the light appears to the human eye, it says very little about spectrum or red and blue light in the bulb. 6000K-7000K is recommend because it looks natural to our eyes, plants though could careless. Two bulbs with the same color temps but different brands often have much different spectrum of light.

Antinic generally is a term that DOES apply to color spectrum, a bulb with a high blue peak. They are also generally sold buy wavelength not kelvin temp.

Basically what I am saying is 6000-7000K is not a "type" of light it is a very wide range in truth. A 6500K bulb could be good for plants or poor based on its spectrum. A 10,000K could be just as good depending on its spectrum.

examples of spectrums:

coralife 6700K nutrigrow

coralife 6700K colormax

coralife 10,000K

Honestly to me all these bulbs look "meh" I stuck with one brand though to show the differences better. I'm not a coralife fan at all. I personally would avoid all these bulbs cuz the spectrums all look bad to me. The nutrigrow and 10,000K are really close, the colormax despite being 6,700K is the least "plant friendly" bulb. None of the forums specific to aquatic plants suggest any specific kelvin rating. Its generally "pick the bulb that looks best to you". Avoid anything really low <4,000K or really high. I run higher then most with 8,000-10,000K being my favorite color temps and it all simply comes down to that I like the crisp clean white light it gives. 6,000-7,000K gives this ugly green haze I dislike a lot washes out all colors.

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