The Planted Tank Forum banner

Will nitrates go down ?

1004 Views 9 Replies 9 Participants Last post by  Diana
Found high nitrates lately and increased the amount of % of my WC.
Did two 50% changes in two days to get it to test yellow instead of Orange. Now I do actually 4g WC but it's a 10g/w a good(2.5") of gravel
and other stuff I'd say it's not quite 9g.
But my test keep coming out about between 5-10 PPM after I do the water change and allow 30 minuits for it to mix completely.
Yes I just tested the tap water while I was typing this and it's bright yellow...not a hint of Orange.
I use the EI low light weekly doses only due to no CO2 but only Excel @
2x the normal doses.
Was wondering if you thought it may eventually go a bit farther down after the WC. I expect it to rise during the week, but since I do use KNO3 it should have enough without starting with some there before I add the ferts.
This new 45% WC is only in it's third week now.
1 - 10 of 10 Posts
Found high nitrates lately and increased the amount of % of my WC.
Did two 50% changes in two days to get it to test yellow instead of Orange. Now I do actually 4g WC but it's a 10g/w a good(2.5") of gravel
and other stuff I'd say it's not quite 9g.
But my test keep coming out about between 5-10 PPM after I do the water change and allow 30 minuits for it to mix completely.
Yes I just tested the tap water while I was typing this and it's bright yellow...not a hint of Orange.
I use the EI low light weekly doses only due to no CO2 but only Excel @
2x the normal doses.
Was wondering if you thought it may eventually go a bit farther down after the WC. I expect it to rise during the week, but since I do use KNO3 it should have enough without starting with some there before I add the ferts.
This new 45% WC is only in it's third week now.
why do you want nitrates lower than 5-10ppm?
Perhas I didn't word it effectively. I would like to start off at 0 nitrates. I test after the WC but before I add the ferts(Macros) and I don't like the idea of adding to what is there. I'd rather be adding to 0. I guess the main point is that it's up around 40 by a
week later when I do the water change and I just thought that starting off at 0 might keep it from getting that high by week's end. At least it doesn't have that redish tint to it...just Orange.
The bio-filter adds nitrates and so does the KNO3. The plants use some of it but
there are few plants now to use it so starting off with 0 or close to that before I
add the ferts may end up at 10-20 by weeks end, which is acceptable.
If you have 40ppm Nitrates by week's end before KNO3 mineral salt is added,then just skip KNO3 dose.
Perhas I didn't word it effectively. I would like to start off at 0 nitrates. I test after the WC but before I add the ferts(Macros) and I don't like the idea of adding to what is there. I'd rather be adding to 0. I guess the main point is that it's up around 40 by a
week later when I do the water change and I just thought that starting off at 0 might keep it from getting that high by week's end. At least it doesn't have that redish tint to it...just Orange.
The bio-filter adds nitrates and so does the KNO3. The plants use some of it but
there are few plants now to use it so starting off with 0 or close to that before I
add the ferts may end up at 10-20 by weeks end, which is acceptable.
I dont see why you want your nitrates to be zero, if they ever get to zero then your plants could show deficiencies, this is the reason you add it back with kno3.

You will never get to 0 if you do a 50% water change on a tank that is showing some nitrate level prior to the water change.

If it is getting too high towards the end of the week/prior to the water change then start cutting down on the amount of kno3 that you dose by half or a third. When doing this you may want to dose a little k2so4 to avoid any potassium deficiencies related to less kno3 being dosed.
Saying the same thing Nilocg just said but stating it a little differently, the ONLY way to get a "true" 0ppm nitrate reading would be to do a 100% water change.

The whole point of doing 50% water changes with the EI system is to make sure that you DON'T bottom out on any of your fert levels, so that the plants are never nutrient-deprived.

5-10ppm nitrates sounds like a really good range for a low tech tank.

If you want your levels to keep dropping over time, you'll have to do larger changes than 50% and stop dosing nitrates.
Sounds like you have a healthy bio-load which is being converted by the BB. Some of that load may be from food debris but there may also be stuff on the floor or in the filter. Water changes as well as some cleaning of the other parts make keep it from running higher. Depends on which is less "evil", cleaning filters or changing water?
Not understanding 0. You should explain that. It's one thing in a non-planted tank.
If the NO3 test shows as little as 5 ppm, I dose.
If it shows over 20 ppm I do a water change.

There are other reasons for doing water changes, of course, but that is just the way I keep the nitrogen level at a reasonable level so the plants are OK without going too high for the fish.


If you really want to start with zero, then do 100% water change twice in a row, and get down under the substrate like this:
Pull some substrate away from a corner and stick the siphon down to the bottom of the tank. When the water gets down to the level of the substrate tip the tank up so the water runs into that corner. (Gotta remove the fish of course)

Refill (a few gallons, no need to fill it all the way) and siphon out the water again through the substrate.

Then refill. You might test just a tiny trace of NO3, but I do not think the tests are really that accurate. You are as close to zero as is reasonable to get in this system.

Then monitor the NO3 without dosing through the week. (Does KH2PO4 and K2SO4, but no nitrogen in any form). The NO3 level at the end of the week is what the fish food is contributing minus what the plants are using.
Now you can figure out how much KNO3 you need to add so the plants are not deficient.

For the next week test the water each time you dose. See what it does, and how much the plants use over 24-48 hours (before the next dose).
Of course this is a combination of fish food and fertilizer that you are testing.
See less See more
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top