Can this be right?

[justinq]

I had been using the EI method to dose ferts in my 30 gallon tank for the last several months, all with great success. The problem was that my ludwigia rufused to be red, and knowing that high nitrates could be the cause, I tested the nitrate levels (something I hadn't done in a long time). They were extremely high, 80-160 PPM (all the high levels look the same to me, so I'm not positively sure). I was previously dosing EI exactly like the forum sticky said to do for a 20-40 gallon tank, minus using Seachem Equilibrium.

Anyway, for a couple if weeks I tried to adjust things a little. I cut the nitrate level in half for the first dose of the week, the only added phosphate afterwards. I did this because I know my phosphate levels are low (I have some green spot algae, and when I finally tested the phosphate it would either be 0 or .5). I decided to scrap the whole EI thing for a while and try to just dose what I figured I needed based on testing. I'm used to dry dosing and prefer it, so I didn't really want to get into PMDD, and I wasn't sure that would solve my problem anyway.

So, after a big water change (probably around 60% or so), I tested the water and found that I had 10 PPM of nitrates and .5 phosphate. I am aiming for a level of around 5 PPM nitrates (based on what I have heard red plants prefer). I added some potassium phosphate, and the usual dose of potassium sulfate (I've kept adding that as suggested in EI since I figure that it can't hurt anything even if I'm overdosing). The next day I added Flourish for trace and Flourish Iron. I tested the water again today figuring I'd have to ad SOME kind of macros. But instead, I found that I still had 10 PPM of nitrates, and about 1.5 PPM of phosphate. I did add some new plants earlier in the week, so maybe they aren't fully established enough to really be depleting the nutrients, but everything has been pearling like crazy and I would have expected SOMETHING to be a little lower.

I know it sounds like the test kit is probably off, but I bought new test kits and they agreed with these readings. I wouldn't be too concerned except that everything I've read seems to imply that for high light and CO2, you're heading for disaster if you don't dose at least three times a week. Does anyone have any suggestions as to how to handle this situation, or what might be going on with my nutrient levels?

[unirdna]

Originally Posted by justinq

The next day I added Flourish for trace and Flourish Iron. I tested the water again today figuring I'd have to ad SOME kind of macros. But instead, I found that I still had 10 PPM of nitrates, and about 1.5 PPM of phosphate.

....I wouldn't be too concerned except that everything I've read seems to imply that for high light and CO2, you're heading for disaster if you don't dose at least three times a week. Does anyone have any suggestions as to how to handle this situation, or what might be going on with my nutrient levels?

Justin,
Every tank is very different. I've even had equal size tanks with similar plant loads have completely different nutrient uptake. Currently, I dose my 48g tank only once every 10-14 days. And I've never needed to dose 3 times a week. But, some have had to do this. Just don't put too much stock in any one experience. Your tank is an individual. The confusing part will come after a time when you've changed no variables, and suddenly the nutrient uptake makes a big, unexplainable change.

[Bert H]

Every tank is very different.

SO TRUE! I agree with Ted completely. I had a similar experience with one of my tanks and found the NO3 around 80+ppm. Let the stickies be your road map, but beware of the wrecks along the way which will make you take different roads.