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nitrate and phos proplems


14 Mar 2009
i have only had my planted tanks for 4 months now,i am new to this hobbie,i have a 260l tank,and i am doing the fert rotine of james tank,for the last 3 months my plants have not bin looking to well,and i just couldent work out wot was wrong,my plants were looking realy dark green and thay was just not growing,i was reading that you could not trust test kits reading,so i was testing but not taking that much notice of them,i was doing the fert rotine and my kh and gh was ok so i thought everything must be right wot i was doing,them i read a post how to calibrate test kits,so i calibrated my nitrate & phophate kh then i tested my tank water to find that the nitrate & phophate were sky high,so i done a 50% water change,and thay were still sky high,i stoped dosing nit & phop and just doses pottassium,iv bin doing this for 2 weeks now and iv just got the nit & phop down the plants are starting to look 10 times better,but am still not dosing them,im using 1/4 tap water to 3/4 ro water and tested my ro water for nitrate & phop and it come out 0,so it cant be in my water thats making it sky high,i no iv mixed the fert solutions up right so it cant be that,i have 2 questions,q1 why do you think my nitrate & phop are sky high,l q2 how would you fine tune your fert rotine so this dont happen again

set up...260l tank,3 x39w t5,co2 injected 4 bps....kh 4dkh.gh 5.gkh nitrate 25ppm phop 2.5 to 3.0 iron ok
fert rotine 40m kno3 3x week,25m ph2po4 3x week,15m trace 3x week, 10ppm mag,10ppm pottassium


Expert/Global Moderator
11 Jul 2007
Chicago, USA
The only conditions under which N03/PO4 are a "problem" are those in which plants don't receive enough of them. Not only is it a waste of time trying to reduce NO3/PO4 levels, it's even more pointless calibrating a test kit and measuring for them. There are quite a few reasons for poor growth performance none of which have anything to do with NO3/PO4. It could easily be that you have too much light or not enough CO2, or even not enough flow to distribute nutrients and CO2. A high tech 260L tank ideally should have around 2600LPH of rated flow. Trying to solve you plant problems by restricting NO3/PO4 is like trying to solve world hunger by restricting distribution of food.

Read EI Dosing with Dry Salts and you see what can be accomplished in a tank with good flow, adequate CO2 and "sky high" nitrates and phosphates.

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