Who Gives A Fish Forums

I've got a 75-gallon planted tank with six Discus, and my plants are struggling. The leaves are turning yellow, and some are melting. I'm using CO2 injection, dosing EI ferts, and running a Fluval Plant 3.0 light for 8 hours a day. Water params are good, 0 ammonia, 0 nitrite, 5 nitrate, pH 6.8, temp 84°F. Any ideas what's going wrong?

Yellow leaves usually mean a nutrient deficiency. Are you dosing macros and micros? Also, check your CO2 levels. Too much or too little can mess with plant health.

I had the same issue last year. Turned out my light was too intense. Try reducing the intensity or duration. Also, what substrate are you using? Some plants need root tabs if you're not using nutrient-rich soil.

Could be a potassium deficiency. I'd up the potassium dose and see if that helps. Also, how often are you doing water changes? Too many can strip nutrients.

Check your CO2 drop checker. If it's not lime green, adjust your injection rate. Also, make sure your ferts aren't expired. I've had bad batches before.

Yo, sounds like your plants are starving. Try adding some root tabs if you're using inert substrate. Also, maybe cut back on the light a bit, yeah?

mossy wrote: ↑Fri Jul 04, 2025 10:59 pm Yellow leaves usually mean a nutrient deficiency. Are you dosing macros and micros? Also, check your CO2 levels. Too much or too little can mess with plant health.

I agree with mossy. Have you tested your water for iron? Low iron can cause yellowing too.

My plants were melting until I switched to a richer substrate. What are you using? Sand or gravel won't cut it for some plants.

Dude, your light might be too strong. Try dialing it back to 6 hours and see if that helps. Also, what's your KH? Low KH can make CO2 levels unstable.

Thanks for the advice, everyone. I'll try reducing the light intensity and upping the potassium dose. I'm using ADA Amazonia substrate, so it should be nutrient-rich, but I'll check the CO2 levels too.