There is no need to have a dark period in your tank. It disrupts the
natural
daily plant cycle and it doesn't help with algae.

Funny you should say that, an hour before i even read your response i had
removed the dark period from my tank.

PH with co2 injection in my tank is about 7.2

According to my calculations, your KH as CaCO3 is 26 degrees, which would
give you 49 ppm CO2 with that pH. If that's correct, it's a little high.


I have conflicting readings, my water authority gives me that value of
289ppm (which i work out as 289/17.86=16.81dKH using the formulae on
http://www.thekrib.com/Plants/CO2/ha...arryfrank.html) but when i test
kh with a test kit from the tap it comes out at about 13 dKH which i believe
is about 22 ppm co2. Id rather go with a test kit of my own water. Im only
bubbling 40 bubbles a minute into my eheim so i cant see that i would be
able to get 49ppm with that, even if my kh was 26. Im probably one of many
who doesnt quite understand kh/gh. My kh test kit says 13 so thats what im
going with!!

Here is what i have been dosing....
20ppm potassium sulphate once a week with water change
0.5 ppm potassium phosphate twice a week, on a tuesday and thursday
No nitrate as yet, still high in my tank.
10ml Kent Freshwater Plant 2x a week on tuesday and thursday.

Nitrates 20ppm
Iron (chelated) .75ppm
Phosphates 1ppm.

I would have thought my phosphates would be lower and that this is
probably
what is causing the BBA. Im going to stop dosing this until my
phosphates
get a bit lower. This is my main priority; i want phosphates to be the
limiting nutrient in my tank. Currently it seems to be something else.

I'm not sure if you meant that you
were adding 20 ppm of K2SO4 or 20 ppm of K from K2SO4,

dosing enough k2so4 to put in 20ppm of K per week, i sometimes put a bit in
mid week as well.

Are those symptoms occuring on new leaves or old leaves?

Its old leaves, so you suggest a possible lack of macros. I think most of my
macros are in abundance, the only one i dont test is K and i add about 20ppm
per week of that.

You also say about increasing my trace mix dosage. Im worried about too much
iron, my current dosage has my iron at about 1ppm currently which i think is
a bit too high. Maybe this will decrease faster as i add mgso4; the
trace+iron will be taken up by the plants at a faster rate, keeping the iron
levels down.

How much Mgso4 do i need to get to the 50ppm you mentioned? Those
calculations throw me!! I think its about 14 tsp a week (using the krib
pages) in my tank of 160 litres, maybe you could confirm this. Seems like a
lot of mgs04.

Thanks for your help

Mark