Why Are My Plants Not Growing Too Well?

[jnms]

Hi, I currently have a low light 1.25w per gallon tank, and I am having trouble keeping my plants thriving. At the moment, they are starting to go yellow with brown spots and are getting very spindly with no leaves growing at the bottom of the plant stems.

Here is my tank setup:
180L tank
Sand Substrate
1.25w per gallon lighting
Tropica Plant Nutrition+ Capsuals inserted into sand at base of plant every 4months
Tropica Plant Nutrition liquid fert, 10ml per week (was previously adding 5ml per week)
Seachem Excel 5ml per day

These are my plants:
Vallisneria nana
Hygrophila corybosa
Hygrophila polysperma
Anubias barteri var. nana

Every thing was growing really well until about 6 weeks ago. I will list out the problems I am having:
The Hygrophila polysperma's leaves are turning yellow with dark brown / black spots. The leaves at the top of the plant remain lush green, midway down the plant are the yellow leaves. At the base of the plant many of the leaves appear to be rotting and / or melting.

Vallisneria nana - has actually been doing very well, and has established itself throughout the tank. However, now the original leaves are falling apart, as though the leaves have been ripped in half. They are also covered in some black algae. The vallis is also starting to thin pretty badly.

Hygrophila corybosa - did wonderful, until it reached the top of the tank. It is a similar story to the polysperma. The leaves at the top are lush green, the mid-stem leaves are yellow with a good number of them melting away. There is some black-algae on some of the leaves. The bottom 1/3 of the plant stem has no leaves at all.

Anubias barteri var. nana - I just learnt that this should really be attached to rock or wood. I have mistakenly planted it into the sand substrate. This hasn't grown much, and recently a lot of the leaves have turned dark. The plant is now starting to look as though it is been eaten by snails - though this isn't the case.


I really don't want to start getting into CO2 injection or adding a soil substrate. Hence the reason I went for low-light, low-demanding plants. However I'm clearly having a lot of trouble keeping lush growth going. So any tips and suggestions would really be welcome!

 

[Amunet]

Well, lemme start off by saying, your tank is just lovely. Wow

As for your plants... I would try adding potassium as well along w/ the other liquid ferts you're using. Flourish makes one. It may not be your problem, but it won't hurt to try it. Whenever I've used it, there is noticeable growth (new leaves) the next day.

Good site that lists different plant deficiencies and what may be the problem
[URL="http/theplantedtank.co.uk/deficiencies.htm"]http/theplantedtank.co.uk/deficiencies.htm[/URL]

 

[snowflake311]

I agree a little feet goes a long way. Add some iron too.

 

[lljdma06]

I agree a little feet goes a long way. Add some iron too.

Your stemplants are too close together. Plant individual stems like an in apart. Then light gets to the lower third. You could also be dealing with submersed vs. emmersed growth.

Anubias attach to rocks or wood, but you know that already. Remove it and check to see the status of the rhizome, if it is rotted, trash the plant. If it is still green and the roots have white tips, cut off all the damaged leaves and attach it to wood or rocks. Should sprout new growth. I've had an inch of healthy, but naked rhizome grow back for me, so it does work, though it takes while.

How often do you change your water and what is you livestock?