Brown Spots

[natalie265]

My Amazon sword has developed brown spots on its leaves. The other plants in the tank appear healthy. Any ideas?

Ph=7
Nitrate=20
DIY Co2
WPG=2

Dose 2xs per week with:
Flourish
Flourish excel
potassium nitrate
potassium phosphate

 

[aaronnorth]

what mixture have you used for the powders/ how much do you dose?
Tank size?

 

[natalie265]

30 gallon tank

For the potassium nitrate i mixed 16 tsps of powder into 1 quart of water and dose about 4 tsps

For the potassium phosphate i mixed 12 tsps of powder into 1 quart of water and dose about 4 tsps

 

[aaronnorth]

is 'one quart of water' 250ml??

Your mixing is quite confusing, because you havent used any exact measurments it is hard to calculate the amount of nutrients you are dosing.

An average tsp holds about 6g or 5ml, so that means you used 96g of KNO3 to 250ml, correct?

 

[natalie265]

I had to convert everything because i had no other way to measure. Sorry, i'm American, we don't really use ml here much. SO let me convert it back...

1 quart=32 oz=946 ml
1 tsp=5ml

Therefore,

potasium nitrate 80ml disolved in 946 ml of water dosing 20 ml
potasium phosphate 60 ml disolved in 946 ml of water dosing 20 ml

Is that confusing enough? No wonder my plant is dying!

 

[aaronnorth]

much better lol,

you have a very high dose of PO4,

"30g to 1000ml of water and adding 10ml per 200L of water would give you a value of 1ppm"

you are adding 60g to 1000ml of water, and dosing 20ml, which will give you around 8ppm of PO4 per dose by my calculations!?

I would cut the dosing back to 5ml, as overdosing on 1 nutrient can stop the plants taking up others. Also, i would add another bottle of DIY and connect it with a 'y' or 't' piece.
Adding some root tabs next to the roots will help, unless you have nutrient rich substrate in which case it wont make any difference.

How old are the plants? As echinodorous species are often grown emeresed, so they die back and produce new, submerged leaves which can take up to 2months.

 

[natalie265]

I've had the amazon sword in my tank for about 9 months. It IS producing new leaves, but i'll have to check to see if these are turning brown as well.

I HAVE thought about adding a second DIY, and i really want to add better lighting. Do you think i'm dosing too much overall given my relatively low lighting conditions (and i'm assuming overall slower growth rate)?

Meanwhile, i'll cut back on the PO4 dose. I DO occasionally use root tabs for the amazons (about every 3 months). The substrate is eco-complete.

 

[aaronnorth]

upping the lighting will need more CO2, and more nutrients. It only makes life harder and beside 2wpg can grow any plant, as long as everything else is up to par.