Plants turning yellow.

[L~C~G]

Hey Guys.

I wonder if you could help me please.

I have got a 120 gal Malawi tank. I have got 4 ludwiga Repens (Started with one and have planted shoots) that have been growing like there is no tomorrow, about 60cm tall. Recently the top leaves have started turning yellow. They are still growing fairly well and have a number of new shoots popping out along the stems but don`t look as vibrant as they used to.

The yellow top leaves are also getting quite a bit of algae growing on them.

I have 4 x T5 tubes all with different spectrum ranges but the lighting has not changed recently so I dont know if that would affect it. The lights run for 16 hours a day.

I do weekly 25% water changes and add 25ml of nutrafin plant gro with every water change. I vacuum the gravel every second week but do not vacuum near any of the plants, only in the open areas.

The substrate is Silica based pool filter sand. The tank has been running for about 4 months. PH is at 7.2, nitrates are around 30.

I have a large piece of driftwood which has been leaching since I put it in but recently is leaching very little.

Here is a pic of the tank before they started turning yellow so you can see the lighting etc.

 

[VNCNT]

perhaps your lighting period is too long... this may deplete the nutrients (i'm guessing iron) in your water

 

[L~C~G]

The lights are on a timer so ill set them to run a bit less and see what happens.

Are there any down sides to possibly switching them on in the morning at 6:00 when I get up, then switching them off at about 12:00 for maybe 4 hours in the middle of the day when I am at work, then switching them back on at about 16:00 and off again at 22:00 when I go to bed.

Would that mess with any natural cycles in the fish/plants at all?

 

[Morphineh]

Hey - Firstly I would suspect an Iron Defiency just as the person has said before and Iron helps form chlorplast for Photosynthesis. Also by leaving your lights on 16 hours a day your plants will photosynthize throughtout this depleting your nutirents very quickly. That being said you could reduce the Photoperiod of your tank to try and fix the problem. Personally I would just stop by a LFS and from just Iron Suppliment Flourish makes one it will cost you 10$ and dose every few days. Read up on Iron Deficency if the older leaves are turning yellow and the leaves very brittle then that's the problem.


Lighting - If you were going to reduce your photoperiod I would just reduce it in a whole (it's way less hassle w/ timers and remembering). That being said by having a photo break during the day it would definetly help you as there is studies on this reduces algae. If you have enough light and ferts you shouldn't haev a problem with this regardless.

As for fish cycles and plants they should be go climatizing to your change just make sure it stays the same and it's not irregular so use timers if you decide to do it. Even if it is irregular isn't not too detrimental, it may cause a little more stress.

 

[jcardona1]

That's a ton of light! I run two T5HO bulbs over my tank for 7 hours, and this is the result:




I would run no more than 8-10 hours for the reasons stated above. Maybe even try running only two bulbs. With all that lighting, you're forcing the plant to require more co2/ferts for photosynthesis. Since you're not providing enough, the plant is suffering and this is what you see. Reduce your lighting, reduce the rate of photosynthesis, and reduce the plant's needs for co2/ferts.