hello,

i know this is probably a very old topic and i'm sorry for the redundancy. i have a 55 gallon tank with 2-54watt t5 6500k lamps, a eheim ecco filter, diy co2. the plants seem to have been somewhat dormant for about 3 months, its been established for about 6 months. i now have green water, i had green water after about 4 months and i got rid of it rather quickly by dropping my light duration from 14 to 12 hours and doing a few extra water changes than normal. its back again and my previous methods are not working. i dropped the lighting down to 11 hours and have done serious water changes. ironically the plant growth now is very dramatic and the fish seem happy, of course i'm not because i can barely see anything in the tank. i must note that photosynthesis and growth appear very high during this green water phase. there is barely one leaf on any plant that isnt pearling. the last time i got rid of the green water the plant growth seemed to slow down, however they were still pearling rather well and still are. so i am assuming that i have an imbalance of some sort but its not negatively affecting the plants. the tank is heavily planted and moderately stocked with fish.

water parameters.
ph 7.6
co2 8ppm
temp 78
gh 8
kh 10
ammonia,nitrite,nitrate = 0ppm

You didn't mention fertilizing. And, for that much light you don't have much CO2, if you have less than 10 ppm. You can't accurately measure CO2 by using the pH/KH table, so I doubt that you have even the 8 ppm you measure that way. If you are trying to have a "natural" tank, with only substrate fertilizing, and low light, you need to suspend that light fixture several inches above the water and reduce the photo period to about 8 hours.

Or, you can start fertilizing with nitrates, phosphates, potasium and trace elements, using the EI method, for example. Adding pressurized CO2, or at least using two or three DIY CO2 bottles will also help a lot. Green water usually starts when there is a sudden little surge in ammonia in the tank, from a dead fish, dead snail, decaying plant matter, uprooted fertilizer stick in the substrate, etc. But, if you keep the tank heavily planted, and the plants growing well, you can usually avoid green water even then.

i have been using seachem flourish and excel based on their recommended dosage. i am using a mixture of flourite and regular gravel for the substrate.
i am using 2 2-liter bottles on the co2 with a home made reactor that appears to be extremeley efficient. i stopped the fertilizer thinking that was the cause of the green/cloudy water. i suppose i should mention that a few weeks ago i UPGRADED to the eheim canister from a standard power filter. i attempted to use as much bacteria from the old filter as possible but now that you mention the ammonia i am thinking that maybe i did cause a minor cycle to occur. and the light is above the water surface at about 4-5".

Flourish provides trace elements, and Excel provides carbon, but you still need NP&K, which is what dosing per EI provides. Those fertilizers will allow the plants to grow faster and healthier and that will help reduce green water problem, not make them worse. If you get a drop checker and use it with 4 dKH distilled water in it you can measure how much CO2 you actually have in the water, as accurately as any cheap method will allow. Then, you can adjust your CO2 if needed.

thanks so much for your input... i am starting to get the hint here but i must admit its strange coming from a fish only setup. more nutrients = algae. makes a lot of sense though. although my plants are growing well, they are not growing "optimally". algae can adjust to different nutrients easier than plants, while the plants will use the same nutrients, they cannot use them efficiently enough to out compete algae if other required elements are not present. did i get that right? thanks again for your help.

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Fertilizers don't cause algae. The absence of fertilizers can contribute to algae starting up, because healthy plants deter algae and unhealthy plants encourage algae. Excessive nutrients are not a worry, assuming you don't have 10X the recommended amounts in the water. Algae don't compete with plants for nutrients, just for light. But, algae require very little in the way of nutrients to grow. Nature has adapted algae to sense good times for growing thru the reproduction stage, and to start growing when those good times are recognized. Some of the factors in "good times" are: ammonia in the water, wide variations in CO2 in the water, dead plant matter or dying plant leaves, etc. Does any of that make any sense?

that definately makes some sense... however, it does concern me considering that my tank is very tidy. dead/decaying leaves are removed immediately, ammonia and nitrites are almost always undetectable, and i change water at the rate of about 10% a day while very lightly vaccuuming the gravel. i have been reading a lot lately and what does make sense to me is that i am most likely severly lacking in nutrients. i have increased lighting dramatically, increased some nutrients, dramatically increased CO2. all of which produced a serious increase in growth of the plants, decrease in larger forms of algae then increase in green water. so my plants have improved, but what i see is that they are now at a level where they are starving for other nutrients. from what you've said and what i've read elsewhere. the green water may have been caused by an ammonia spike, but i'm having a hard time believing that is what is sustaining it. its now going on two weeks of green water. not getting worse, some days very slightly better. luckily its not solid and i can still see my angels.

It sounds like everything you are doing now is right, except I would still keep the light at a reduced rate. Max 10 hours duration, and raise it several inches above the water.

Quote from Vaughn, "Algae don't compete with plants for nutrients, just for light."

This might be the change that will get your tank stabilized.

Good luck!

-Mike B-

i changed the timers so we'll see how it goes for the next few days. i also noticed that during the past few water changes that i raised the level a slight bit. no more than 1/4 inch. since i'm at somewhat of a loss because the tank has been stable for a while, i've decided to set everything back to exactly the way it was when it was stable. unfortunately raising the light is a bit difficult without making custom brackets for it. obviously though i think raising the water level is the same as dropping the light closer to the water. i haven't changed the wattage of the lights but i did change the bulbs from 10000k (stock bulbs for that fixture) to 6500k bulbs. would anyone disagree with that change. lighting seems to be a rather difficult and detailed topic and i've read a lot and i have gathered that 6500k is a better choice.

[quote=FacePlanted;19897]Quote from Vaughn, "Algae don't compete with plants for nutrients, just for light."


i believe i was under the impression that if important nutrients are lacking then plants cannot grow at an optimal rate therefore possibly not consuming phosphates at a rate sufficient enough to keep them from algae. add that with higher light and you have a disaster waiting to happen (green water )

i guess in simpler terms...
high light, CO2, low nutrients=algae
high light, CO2, high nutrients = plant growth ???

this is the balance everyone is referring to right?

please bare with me. i've gone from fish only, to a reef tank, to fish only, to a planted tank over the past 10 years... only the past 6 months involve the planted tank.