Water Investigation
Well, by the end of the week, the TDS in water in the 30-gallon had sky-rocketed. The other tanks had no increase, so my assumption was that the higher fish load was pumping up the nitrates faster than the plants could take them up. In fact, half-way through the week, I just bumped up potassium and stopped dosing nitrates.
However, every hypothesis should be tested. It was kind of bothering me that my 5-gallon, for instance, has a very high fish load and very low plant load, yet did not show elevated TDS over a week. So I went ahead and tested the nitrates, and sure enough, they were only 5 ppm. That means the increase in TDS is from other sources; presumably over-fertilization. Not surprisingly, phosphates came up off the charts (10+ ppm). If I could test for potassium, I would venture to guess it would come back very high (although I have symptoms of potassium deficiency -- pinholes in older leaves). I'd test for iron excess, but that test kit sucks...
Regardless, it appears that dosing nitrates wouldn't be a bad idea. So after this water change, that is exactly what I will do. Might as well do this EI thing right (maybe no phosphates this week).
As a reminder, for a 30-gallon tank (per APC):
Because I'm used to dosing everyday, anyway, and from many months of success with potassium dosing, combined with my heavy fish load, I'm going to adopt this similar, but different dosing strategy:
I'm still dosing phosphates and Plantex every other day. I read somewhere that they can interact poorly with each other (combining and coming out of solution), so I'll stick with dosing them on alternate days.
It comes out more or less to the same quantity of fertilizer, just a little less NO3, and a little more potassium. That's the new strategy, though I should probably be prepared to migrate toward the strict EI method (though I swear I've seen some dosign regimins with K2SO4).
However, every hypothesis should be tested. It was kind of bothering me that my 5-gallon, for instance, has a very high fish load and very low plant load, yet did not show elevated TDS over a week. So I went ahead and tested the nitrates, and sure enough, they were only 5 ppm. That means the increase in TDS is from other sources; presumably over-fertilization. Not surprisingly, phosphates came up off the charts (10+ ppm). If I could test for potassium, I would venture to guess it would come back very high (although I have symptoms of potassium deficiency -- pinholes in older leaves). I'd test for iron excess, but that test kit sucks...
Regardless, it appears that dosing nitrates wouldn't be a bad idea. So after this water change, that is exactly what I will do. Might as well do this EI thing right (maybe no phosphates this week).
As a reminder, for a 30-gallon tank (per APC):
- 1/4 tsp KNO3 3x/week
- 1/16 tsp KH2PO4 3x/week
- 1/16 tsp Plantex CSM+B 3x/week
Because I'm used to dosing everyday, anyway, and from many months of success with potassium dosing, combined with my heavy fish load, I'm going to adopt this similar, but different dosing strategy:
- 1/16 tsp KNO3 7x/week = 1 pinch 7x/week
- 1/16 tsp K2SO4 7x/week = 1 pinch 7x/week
- 1/16 tsp KH2PO4 3x/week = 1 pinch 3x/week
- 1/16 tsp Plantex CSM+B 3x/week = 1 pinch 3x/week
I'm still dosing phosphates and Plantex every other day. I read somewhere that they can interact poorly with each other (combining and coming out of solution), so I'll stick with dosing them on alternate days.
It comes out more or less to the same quantity of fertilizer, just a little less NO3, and a little more potassium. That's the new strategy, though I should probably be prepared to migrate toward the strict EI method (though I swear I've seen some dosign regimins with K2SO4).
posted by k-maub @ 2:08 PM
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