Lifespan of DTPA in aquariums
Interested in hearing other members experience with the length of time DTPA iron remain effective in your aquariums.
I did some research and I've read anything from a few days to months. If I'm not mistaken, I've seen Tom Barr say a few days on one thread and then a week on another thread.
I don't have an iron test kit, but in my tank (PH7.6), I think it lasts about 48hrs. I'm going by how green the plants look. If I skip a dosing, the plants turn pale green. I can't say this is accurate in any way because I'm only going by color.
With my 7.6 PH, I only lose about 20% as DTPA is stable up to 7.5, so it shouldn't be an issue. I know other factors like light, oxygen, etc will shorten the iron's lifespan, but seeing people claim days and months is sort of confusing.
There's also the issue with substrate. With high CEC, the substrate will absorb the iron, no CEC, then the iron will linger in the water.
I run a low tech set up with weekly 10% water changes, inert substrate with no CEC, so I'm definitely worried about build up if DTPA can last longer than a week.
Would love to hear other people's experience with DTPA.