I have a planted aquarium that I've been working on for a while and I'm still trying to get my plants to grow nicely. From doing a bit or research, I believe that my aquarium plants may need additional iron. How can I get a small amount of iron to my aquarium plants? (without adversely affecting my clown plecostomus and ghost shrimp) Also, I don't have the money to purchase expensive fertilizers so a cheap or free way would be best.

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    Hi, did the answer work for you or did you solve the problem in other ways? I have Egeria densa plants which are supposedly requiring large amounts of iron so I had the same problem (but it was some time after you had posted this question). However, I found the liquid fertilizer easily in my local pet store: 30 mL of liquid for the price of 9 PLN (my local currency; it is around 2.40 USD); dosage is 1 mL of liquid per 10 L (2.6 gallons) of aquarium volume so it is highly efficient and cheap; I am just wondering how much more expensive could the fertilizers be where you live. – lila May 3 at 0:18
  • What is more, the problem with existing answer is that iron oxides and hydroxides (constituents of rust) are almost insoluble in water so only a minuscule amount is available to plants (solubility of these compounds is also highly dependent on pH, with a relationship that an increase of one unit in pH causes inorganic iron's solubility to drop 1000 times down [1st-source] and [2nd-source]. In liquid aquarium fertilizers, you could look for "chelate iron" (organic form) which is... – lila May 3 at 0:35
  • ... highly soluble in water and highly bioavailable for plants. I would also be concerned about potential contamination danger while using iron nails, etc. because they could contain toxic heavy metal impurities besides iron, such as lead, nickel and cadmium. – lila May 3 at 0:49
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    @lila I ended up using a liquid fertilizer. It seemed to be making a difference in the plants, but I'm not sure how well it worked long-term because I had to get rid of that tank due to moving to a new house. – Jacob B May 3 at 5:56

Pushing nails or similar size bits into the gravel , make sure the are not galvanized. They will turn red/brown with rust fairly fast but being buried they will be out of sight. Another very fast possibility is putting a small bit of steel wool ( NOT with soap) into the filter system. You give me an idea; long ago I grew cryptocorne so well I sold it to a pet shop. That was in an angle iron tank and rust often fell into the tank. Since then crypt growth has only been fair in many different tanks; maybe they need iron.

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