The Planted Tank Forum banner

Trouble Diagnosing Possible Nutrient Deficiency

1092 3
I'm new to this hobby and have had this tank up and running for about 3 months. I purchased a large amount of various plants from a local grower and threw them in the tank.
Some are doing well, others not so much. I don't expect much growth since I'm not injecting Co2 but some plants are deteriorating.

It is fully cycled, ammonia and nitrites always 0 but nitrates are always low (<5 ppm) (bio load cant keep up with plant demand?).
pH is usually 7.8-8, Water's at 25 degrees C, GH is 8 degrees and KH is 7 degrees.

I've started dosing seachem flourish Nitrogen, Phosphate, potassium, and excel together twice per week at the dosages recommended on the bottle, and comprehensive (micro nutrients) once per week on a different day for roughly 4 weeks and haven't noticed a change.

Tank is 120L and I normally do a 40% water change once a week for the sole purpose of removing tannins from some driftwood and vacuuming the fish poo.
Lighting is on a timer for 8 hours per day with one big LED strip running the length of the tank and one smaller LED strip half the length of the tank.
I used to the lights on for 12 hours per day but staghorn and BB algae were forming. I seem to have a mild amount of diatoms still present however they seem to be reducing?

I used root tabs when I started but I've just used plain sand for the substrate which I am beginning to think is the cause of my problems? Java ferns and such that pull nutrients from the water column seem to be doing fine but my swords, stems, and grasses are struggling?

New growth seems to be stunted and old growth seems to be browning and dying. Water sprite in particular is becoming porous and disintegrating.
Here is a link to some pictures:

The tank is reasonably stocked with 2x Bristlenose Plecos, 5 Guppies, 5 Zebra Danios, 10 Cardinal Tetras, and about 20 Cherry Shrimp.

I'm at a loss as to what else to try at this point.
Appreciate the help. :)
1 - 1 of 1 Posts

· Registered
6,876 Posts
Hi @Jackbrew,

Welcome to TPT!

I looked at your pictures and your dosing levels. You are only dosing about 2.2 ppm of nitrogen per week (2 X 2 ml) and likely under-dosing the other nutrients as well. I would start by increasing dosing of all nutrients except Seachem Excel to double your current level and see if you can obtain 10.0 ppm of nitrates with your test kit. Keep the tank at this level for two weeks and see if the plants show a positive response with greener color and better growth.

The broadleaf watersprite (Ceratopteris cornuta) in your tank is showing physical damage, not a nutrient issue. I suspect the plecostomus are enjoying a salad, especially after the lights go out. I don't use plecos in my tanks specifically because they seem to enjoy my plants as much as I do. For algae control I use Siamese (not Chinese) Algae Eaters (Crossocheilus oblongus) and Otocinclus which don't damage my plants.

Let us know how things go! -Roy
1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.