Thank you all
Bonsai - I hadnt thought about removing 50% of the water - good idea. I will check if my plecos, clowns and angles are going to be OK in the resulting water once I finish replacing the best part of the substraight.
Rex Grigg, trenac I would really appreciate your support. You guys may be correct. I have only being keeping fish for a little over 18months. To answer some of your question:
Do you fertilize? Yes but not for the first 6 months - Stopped once the algae started to spread.
With what? Flourish iron and Kent Pro-Plant.
How often? Once a week (I have to admit to being a bit erratic with both once I noted the plants dying
Do you test for nitrates? At least once a month currently 5mgl
What kind of plants? No red plants they all die.
Vallisneria this tends to grow well.
Java fern after 4 weeks completely covered in dark green algae
Echinodorus never does well
Stargrass I really like this plant grow very well to begin with then stop growing
Crinum onion plant It can get covered in dark green algae.
Hygrophila - water wisteria never grows in my tank!
Egeria densa pond weed currently growing but again the leave at the bottom tend to die off
Bacopa caroliniana Giant Bacopa never grows well
What are the symptoms before they die?
There tends to be a large amount of algae on the leaves. Some of the larger plants tend to go yellow then brown then they disintegrate. Some plants get overrun with think dark green algae almost impossible to remove from the leaves.
I have had hair algae, slime algae, black algae (Phosp in control now algae undercontrol the plants tend to lose leaves from the bottom.
How often and how large are your water changes? 26 gallons once a week
Do you have CO2? No
Phosphates 0.25mg/l (TAP water can contain up-to 15mg/l have been using RowaPhos for the last 3months to reduce Phosphates)
Iron Fe 0.00
Underwater heating and UV 25watt. XP3 and 2028 plus a single air pump.
1 X T5 54watt white Actinc 10k or 14k not sure
2 X T8 36watt Aqua flora
2 X T8 36watt Aqua power glow
Substraight box of laterite not sure of weight but cost £22 added on top of very first layer of fine gravel just above the heating cable covered with up to 2inch fine gravel finished off with medium gravel
sorry for going on - your help is most needed - will do what ever it takes!
thanks again everyone