Java Fern Fertilizer Advice Needed

[AndreaW]

I've only had these Java Fern plants since the end of January so they are still adjusting (dark spots on original leaves). However, I'm seeing quite a bit of new growth (roots and new leaflets growing from the tips) so I added some fertilizer: 

• 3/5 .7mL Flourish
• 3/8 5mL Leaf Zone

A few days after adding the fertilizer, I noticed the young leaf tips on my Javas were beginning to darken. I haven't fertilized since then and have been watching the new growth, which has continued to darken at the tips. I finally got my Easy Green fertilizer, so I was going to switch over to that, but wanted advice before I add any more.

Here are my current tank parameters:

• 10 Gallon corner tank with original LED lights built into lid (12 white & 3 blue LEDs) all in a row, and water lettuce shading most of the tank surface. Lights are on a schedule 11am-7pm and it does get natural light in the morning and about 20 minutes of direct sunlight that hits the front corner of the tank.
• pH 7.6
• KH 7° (125ppm)
• GH 16° (286.4ppm)
• Ammonia 0ppm
• Nitrites 0ppm
• Nitrates <5ppm
• Phosphate .5ppm
• Temp 79°F
• Plants in the tank: Java Fern, "Windelov" Java Fern, and some other unknown plants that might be Anubias, Crypt & Sword? All other plants are beginning to put out new growth and I think are doing fine so far. 

 

 

 

Sorry, some of the pics are sideways and I can't get them right-side-up.

I'm assuming I need to add more fertilizer since my Nitrate/Phosphate is are low, but when the tips started turning dark I worried I might have overdone it. I've tried researching but some people say it's typical Java growth and others say its a nutrient deficiency.

If this was a houseplant, I would think I over-fertilized or over-watered it!  Can you over-fertilize aquatic plants? I would assume you would just grow algae at that point since the plant only absorbs what it needs, right?

 

[Mmiller2001]

Both of those fertilizers don't have a significant source of NPK. You will need add that along with either of those. But only use flourish or leafzone, not both when you begin using a NPK source. I personally would use flourish over leafzone. 

[AndreaW]

On 3/14/2022 at 12:33 PM, Mmiller2001 said:

Both of those fertilizers don't have a significant source of NPK. You will need add that along with either of those. But only use flourish or leafzone, not both when you begin using a NPK source. I personally would use flourish over leafzone. 

Originally I bought the Flourish (advised by the LFS), but then I read that Java Fern need more Potassium so I got the Leaf Zone. If I use Easy Green, I won't need the Flourish or Leaf Zone, right?

[Mmiller2001]

Easy Green is low on P, K and Fe in my opinion. You might could use both. You would just need to calculate totals.