Yellow Leaves - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 5 Old 11-04-2012, 01:57 PM Thread Starter
Yellow Leaves

About 4 months ago I added some hygrophilla corymbosa to my heavily planted well established 29 gallon low light/low tech tank figuring I would give this plant a try. All the plants I already had in there were over a year old and doing fine and were showing good growth. The only ferts I was adding at the time was Seachem Comp. once a week. The hygro started to turn yellow around the edges and was developing holes in the leaves. I added some Flourish potassium for the holes and some Flourish iron for the yellowing. Thatís when all hell broke loose in my tank.

All of my anubias (I have at least 25 of different varieties) started to turn yellow around the edges. I stopped adding iron and potassium (still adding Flo. Comp.) but the leaves keep turning yellow. Everything I have tried has had no results. I even added some new anubias about 3 weeks ago and those leaves are starting to turn yellow. The hygro has since died and been removed.

What I donít understand is that I have a 10 gallon tank right next to the 29 and all of the plants are healthy. The only difference between the 2 tanks is that the lights are the same. This obviously means that the 29 gets less light because of the greater depth of the tank. But again everything was OK until I added additional ferts.

Tank Parameters:
Lighting: Life-Glo 6700K T8 15W Only about 6 months old
PH 7.2
Ammonia 0
Nitrite 0
Nitrate 20
dGh 9
dKh 6
TDS 265

I ordered a new bulb online and that will be here in a couple of days but I donít know what else to do.
If anyone has any ideas I would sure appreciate some help. Again please remember I didnít have any problems until I added iron.

Thanks in advance for any help.
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post #2 of 5 Old 11-04-2012, 02:24 PM Thread Starter
Correction--Make that a 20 watt bulb.

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post #3 of 5 Old 11-04-2012, 05:20 PM Thread Starter
After doing some further reading I believe this could be a nitrogen or phosphate deficiency. Does that sound possible?

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post #4 of 5 Old 11-04-2012, 05:42 PM
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Originally Posted by trapperwolves View Post
After doing some further reading I believe this could be a nitrogen or phosphate deficiency. Does that sound possible?
No. The problem is mainly the iron. You can see the brown patches on the leaves, within the yellow? Those are deposits of excess iron in the leaves. The potassium should not be a problem, most sources say that overdosing potassium will not cause problems.

The GH at 9, is this 9 dGH or 9 ppm? I assume the former, 9 dGH, so that should be fine for the "hard" minerals which are at insufficient levels in prepared fertilizers since the tap water supplements calcium, magnesium, etc.

To get this tank back to what it was, do once weekly water changes of half the tank, and the day following dose (only once) a 1/2 teaspoon of Flourish Comprehensive.

To the Hygrophila corymbosa. This plant needs good (= bright) light and high nutrients. I had no luck with it, it sort of "managed" for a few weeks, but then gradually declined with symptoms exactly as you describe. This was in a tank with two 4-foot tubes over it, but still not sufficient. Most stem plants are fast growing, and that means they need more light and more nutrients.

A single Life-Glo T8 tube is minimum over a 29g; mine is doing fine with this, but it is low to moderate light. Replace the tube after 12 months. This is one case where the less expensive Daylight tubes do not work well, they are not of sufficient intensity. The Life-Glo, and a couple others, are made for brighter intensity.

Back to the nitrogen and phosphate. The latter is usually more than sufficient from fish foods, even when not present in tap water [there might be some in yours]. Nitrogen occurs as ammonia and plants grab this and convert it to ammonium. You will rarely have nitrogen deficiencies in natural planted tanks with a fish population.

Final comment on iron. This often comes up, members thinking they need more iron. Your example is a prime one why this is never advisable, and why I always recommend against adding iron. Iron is only a micro-nutrient, like copper, zinc, manganese, nickel, and some others. Plus, they are heavy metals, highly toxic to all life forms at elevated levels. Flourish Comprehensive is a balanced nutrient supplement, meaning the various nutrients are in proportion to each other as required by plants. If the light is low or moderate, and CO2 is not being diffused, only in rare cases will additional supplementation of some nutrients beyond Flourish be necessary. And in most cases, iron will not be the one.


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 youíre going to take it under your wing then youíre responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Last edited by Byron; 11-04-2012 at 05:50 PM.
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post #5 of 5 Old 11-04-2012, 06:44 PM Thread Starter
Thanks for your response Byron. That is a reading of 9dGH not 9 ppm.

I knew the hydro needed more light but thought I could help the plant by adding some iron. I didn't think it would have such an adverse affect on the other plants. I have been doing 50% water changes every week and hopefully my plants will be able to recover from the iron over dosage.


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