Help with dosing please..

[bramswell]

I hope someone can help with my dosing.

i have made a fert mix of ..

6 tsp Potassium Nitrate (KN03)
2 tsp Potassium Phosphate (KH2P04)
6 tsp Magnesium Sulphate (MgS04)
2 tsp Trace Mix
plus ascorbic acid and potassium sorbate
500mls water

dose rate of 5mls per 50lts
i have a 180lt tank medium planted and have been dosing 20-25mls per day along with 5ml excel and injected c02 at 1 bpm (drop checker green)

i have noticed some of the plants have slightly brown tips/edges so i checked the nitrates of the water.
now i know test kits arent perfect but before i added c02 and more light, nitrate would be around 20ppm with normal plant growth
but today about 3 hours after dosing i got a reading of 0ppm (second set of lights not on yet, so only 1.25wpg for the first 3 hours then 3.2wpg for 4 hours then back to 1.25wpg for 3 hours)

so are the plants using all im giving them in a few hours and should i be dosing more and if so how much?

I'm not very good at working out how much ppm of whatever i need to reach X amount so any help would be good as i dont want to just start adding more and more ferts if its something else i need to do.

 

[bramswell]

thanks

the MgSO4 has been increased, it would usually be 12tsp but had run out when i made the last mix, this has now been adjusted.
the trace mix was done at 2tsp to account for the mix only being 2.4% iron fe and not as some ive seen at 13%
i did wonder if using 1tsp of mix then using some of the seachem iron

i use it mixed in water as sometimes i have to get others to dose the tank if im away and a daily dose of 20ml is easier than making up loads of dry mixes for every day.

will it cause any harm if i was to double my dose of my mix to 40mls a day for a couple of weeks and see how the plants respond as i think the yellowing of the edges is potassium deficiency...would that dose be safe for the fish

 

[bramswell]

If you think its a Potassium deficiency why not try increasing this first with your current dosing?

not sure how to do that as i thought the potassium was coming from the potassium nitrate and phosphate.. is there another way to add that
the only reason i say its a potassium deficiency is cuz thats all i could find in the book i have

 

[bramswell]

MgSO4 has been adjusted now to the correct level, that is now 14 tsp, so i think i will try some seachem iron and see if that has made any difference in a few weeks