# [Wet Thumb Forum]-Hornwort and low light



## jaybird002 (May 12, 2006)

Is it possible to grow hornwort in low light, specifically 40 watts of normal florescent light for a 29-gallon tank. When I buy a batch of hornwort, it grows beautifully at first, with long, graceful stems and nodes of leaves close together. It often grows to several times the length of the original plant. After weeks or months it gets clogged with algae and growth slows. Stems become spindley, with more space between the nodes. I take out the algae clogged parts, hoping the rest will grow. After a while it doesn't. Needles start falling off, and I have to throw the whole plant out.

So what is the problem? If it is just insufficient light, why does it grow so well at first? Are nutrients being depleted? What changes? Ammonia and nitrites are 0. Nitrates 20. PH about 7.8. I assume that substrate (plain gravel with occasional Flourish tabs) is not a factor for floating plants. Anibus nana grows great, although covered with algae. Swordplant likewise, now that I added Flourish tabs.
Thank you for any advice or suggestions.


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## jaybird002 (May 12, 2006)

Is it possible to grow hornwort in low light, specifically 40 watts of normal florescent light for a 29-gallon tank. When I buy a batch of hornwort, it grows beautifully at first, with long, graceful stems and nodes of leaves close together. It often grows to several times the length of the original plant. After weeks or months it gets clogged with algae and growth slows. Stems become spindley, with more space between the nodes. I take out the algae clogged parts, hoping the rest will grow. After a while it doesn't. Needles start falling off, and I have to throw the whole plant out.

So what is the problem? If it is just insufficient light, why does it grow so well at first? Are nutrients being depleted? What changes? Ammonia and nitrites are 0. Nitrates 20. PH about 7.8. I assume that substrate (plain gravel with occasional Flourish tabs) is not a factor for floating plants. Anibus nana grows great, although covered with algae. Swordplant likewise, now that I added Flourish tabs.
Thank you for any advice or suggestions.


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## dwalstad (Apr 14, 2006)

40 watts sounds like enough light. Since Hornwort doesn't have roots, its at a disadvantage via rooted plants for nutrients.

If your swordplant is growing well, then it could be iron deficiency. The swordplant can pull iron out of substrate debris whereas Hornwort depends on water iron. Here floating plants are at great disadvantage to rooted plants.

Another possibility; if you're not doing water changes and/or you have softwater, the Hornwort may not be getting enough calcium and/or potassium. Have you measured water hardness? Hornwort is a hardwater plant.

These are the most obvious reasons for poor Hornwort growth.


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## mrmag (Jan 12, 2005)

I have observed the same effects you mention in your email Jay. I think it's iron as well as I have witnessed this. Does great at first because there is iron in the water column, depletes very soon.

I've also had algae problems in hornwort. Ended up removing 90% of it because it was spreading all over the tank... checked phosphates and they were very high. Stopped using NovAqua which has a PO4 buffer, now the problem is subsiding as [PO4] drops.

mike


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