kekon

My filter media look exactly the same before cleaning

I've never noticed that but as far as i know many iron compounds turn into rust which takes brown colors. However in a planted tank the filter also gathers many other organic particles which in contact with iron cause filter media take black colors (i think it's mostly caused by bacteria activity)

YRus

Thank you for share.
Did you measure TDS in the experiment?
If you did it, could you list TDS values of the experiment?

kekon

Unfortunatley i've never measured TDS... but i can list all the values and chemical compounds i add to my tank during RO reconstitution as well as during daily fertilization:

RO Reconstitution:

Ca - 29 ppm (CaCO3) + 2 ppm (CaCl2) = 32 ppm
Mg - 9 ppm (anhydrous MgSO4)
K - 20 ppm (K2SO4)
Cl - 5.1 ppm (CaCl2)
Na - 0 ppm (but small Na amounts comes from DTPA chelator, but i don't know how much)
SO4 - about 60 ppm

Daily fertilization:

macro:

NO3 - 0.5..1 ppm (KNO3 + NH4NO3)
NH4 - 0.05..0.1 ppm (NH4NO3)
CO(NH2)2 (urea) - 0.33 ppm
K - 1..2 ppm (KHCO3)
PO4 - 0.2..0.25 ppm (KH2PO4)

micro (also daily doses):

Fe - 0.05 ppm (DTPA "Dissolvine D-Fe-7" produced by "Akzo-Nobel")
Mn - 0.029 ppm (EDTA + DTPA Mn chelator; 14% Mn)
Zn - 0.00285 ppm (EDTA + DTPA Zn chelator; 14% Zn)
Cu - 0.0017 ppm (EDTA + DTPA Cu chelator; 12% Cu)
B - 0.0014 ppm (H3BO3 - boric acid)
Ni - 0.000143 ppm (NiCl2*6H2O)
Co - 0.000143 ppm (CoCl2*6H2O)
Ti - 0.00043 ppm ("Tytanit" liquid biostimulator)

BryceM

Bluesboy, this is a bit off Kekon's topic, but I'd guess that your iron is forming insoluble complexes and falling to the substrate. It probably doesn't stay in the water column very long.

SnakeIce

The one thing that puzzles me about that is the Cl. I know cloride from things like NaCl and CaCl have quite a negative effect on some plants growth even in small amounts. When I was useing CaCl to dose calcium I had mixed results in that being any help for the cupped leaves caused by Ca shortages.

And Cl2 we try to remove from the water if we are keeping any organisms.

I'm at a loss to explain why either would be dosed.

BryceM

Cl (chloride, an ion) is a required nutrient for both plant and animal growth. Don't confuse this with Cl2, which is chlorine the gas. They may be a bit similar from an elemental point of view but their chemical reactivity and biologic action are completely opposite.

BluesBoy

I hope this is on topic because it's how to balance makro and micro.

I have done some tests. At the same time I took a water sample from the substrate (under the gravel and just above the bottom glas), and one from the water column.
I have measuerd NO3, PO4, pH, kH and Fe. All are the same except the Fe. It's out of range in the substrate (on the right-hand side):
http://www.bluesboy.se/viewimage.php?id=671

I wonder why the Fe is absorbed in the substrate and why it's still measureble by the Fe-test
Any ideas?

kekon

I have some doubts concerning Cl. I used CaCl2 but in small amounts; the Cl concentration has never been higher than 15 ppm. I didn't notice any issues at such Cl level but perhaps it was too short period (2 weeks) to confirm it was safe for plants.
Some folks reported problems using CaCl2 but i think they used much of it. I've never known how much Cl plants really need. Rivers and lakes that are not contaminated and where aqautic plants grow, usually have low levels of chlorides - no more than 5 ppm (i read about it from literature available in the internet). In tap water however, we often measure much higher levels of chlorides. It's usually 10..50 ppm ppm or higher. Maybe some issues he have with our plants are caused by higher Cl levels but i'm not sure. The strange thing is that higher Cl levels in the tap are not as harmful to plants as the same Cl levels added artificially from salts such CaCl2 or NaCl for example. Anyway, i try to add no more 10 ppm Cl when i reconstitute RO water. I know that KCl (potassium chloride) is safer than CaCl2 (as a source of Cl only).
When it comes to SO4 i didn't see any negative effects even at higher concentrations close to 100 ppm.

SnakeIce

There is a thread here that discusses some experience with using CaCl to dose calcium to high levels for inverts. These guys also keep plants and experienced a great change in growth in a positive direction when they switched to a different source of Ca.

My understanding from reading the above thread and documents linked to in that is that Cl levels can inhibit plants ability to uptake N, and that different plants have different tolerance levels for Cl.

If you know you aren't getting Cl from any of your other dosing compounds I might treat it like a micro nutrient and take it back to a .5-1 ppm level.

Glouglou

Kekon, where do you keep your level of iron?