What's Wrong With My Plants? Good for a month, then decline

HI all

I hope some of you nice people could offer some advise as to what's wrong with my plants.
I've been keeping live plants for about a year now and when I indtorduce a new plant it is fine for a month or so and then they go a bit funny (see the attached pictures)

I have a 90L (18 uk gallons for our friends over the pond) tank with 2x15w flurescent T8 lights.(corrected) JUWEL Aquarium | Day-Lite | purchase online
Water temp always between 23-26c
No3 / Nitrate 0-10
No2 / Nitrite 0
GH / General Hardness 8d (roughly 80MG/L (ppm) if my conversion is correct))
KH / Carbonate Hardness 6d (roughly 107MG/L (ppm) if my conversion is correct)
PH 7.2
CL2 / Clorine 0

I have CO2 pumped into the tank and the reader always shows a constant green, bubble counter is about 4 p/sec

I fertilise regularly

Any advise as to why my plants look this way will be much apreciated.

2018-04-22 18.52.28

• madmaniakid
• May 3, 2018

2018-04-22 18.51.54

• madmaniakid
• May 3, 2018

2018-04-22 18.52.15

• madmaniakid
• May 3, 2018

 

Photos didn't attach, could you repost them?

 

What do you fertilize with?

What kind of substrate do you have?

It looks like algae on the leaves - does it come off when you rub it?

Are the Anubias or ferns planted?

 

Looks like a dark algae to me! try rubbing the leaves and see if that helps.

 

HI madmaniakid

2X38 watts over a 21 gallon (U.S.) tank is an intense amount of light; what is the photoperiod (light duration) per day? With that much light CO2 is definitely called for and I am glad you have it but sufficient nutrients are required as well. Hopefully you are dosing dry fertilizers using the Estimative Index (EI) method because most pre-mixed fertilizer will likely be insufficient. This is further indicated by the fact that your nitrates are <10.0 ppm. Ideally we target 20.0 ppm for nitrates.

Along with the GSA (Green Spot Algae) which could be caused by insufficient phosphorus (phosphate) dosing the other condition I see in your photos is the leaf margins curling (rolling) under along the longitudinal axis as well as some chlorosis (yellowing) of the older leaves. This is typically an indication of a magnesium deficiency.

C. Interveinal chlorosis. Interveinal chlorosis first appears on oldest leaves

1. Older leaves chlorotic, usually necrotic in late stages. Chlorosis along leaf margins extending between veins produces a "Christmas tree" pattern. Veins normal green. Leaf margins may curl downward or upward with puckering effect. Necrosis may suddenly occur between veins. Potassium or calcium excess can inhibit uptake of magnesium...magnesium deficiency

When the external magnesium supply is deficient, interveinal chlorosis of the older leaves is the first symptom because as the magnesium of the chlorophyll is remobilized, the mesophyll cells next to the vascular bundles retain chlorophyll for longer periods than do the parenchyma cells between them. Leaves lose green color at tips and between veins followed by chlorosis or development of brilliant colors, starting with lower leaves and proceeding upwards. The chlorosis/brilliant colors (unmasking of other leaf pigments due to the lack of chlorophyll) may start at the leaf margins or tips and progress inward interveinally producing a "Christmas" tree pattern. Leaves are abnormally thin, plants are brittle and branches have a tendency to curve upward. Stems are weak, subject to fungus infection, usually leaves drop prematurely.

I suggest along with increased dosing of your macro-nutrients adding some magnesium to your dosing schedule; magnesium sulfate (aka Epsom Salt) is a good, inexpensive source of magnesium. I can help you to determine a dosage amount to start with but I need to know if you do weekly water changes and if so how much?

 

HI guys, sorry for the late response (work commitments)

So to answer some of your questions, the subrate is just normal gravel, most of the plants are water feeders or grow on rocks which the ferns are all on lava rocks.
If I rub the leaves with my finger nail it does not come off, but it does look as though it's on the leaves, the ferns looks like it's in the leave (deficiency).
I use JBL ferropol for fertiliser Which is meant to contain all the micro-nutrients needed.

I forgot to mention that my filter has a bag of Silikat in JBL SilicatEx Rapid which removes silicate and some phosphate as I had a problem in the past with diatoms so I used it ever since.

My lights are on for 8 hrs a day. Sorry I got my numbers wrong it's 2 x 15w T8 (I looked quickly and saw the 38 from the length as they are 438mm)
Also I was always lead to believe that nitrates should be kept at <10 if possible for the health of the fish. Also do you recommend I remove the silikat bag as it does remove some phosphates

I do a water change every sunday no more then 20L as I fill 2 10L buckets.

 

It could be an issue with the lack of macros. Green spot algae (the spots that are on your leaves that won't rub off) is caused by a lack of phosphates, so I'd take out your chemical media that removes it.

You can let nitrates get above 10 ppm, but I'd keep them under 20 ppm.