Frogbit dying, don't know why

[Masspanic]

Hey guys I have a little bit of a weird situation. So I’ve got this frogbit and it looked great when it came in. I put some in my betta tank and some in my 40g.

The frogbit in the betta tank is doing well. That tank has a low flow internal filter, is kept at 78F, has a pH of 6.8, and no significant nitrates or anything else.

The frogbit in my 40g is dying. The tops of the plants are turning yellow then darker and mushy and disintegrating. All of the rooted plants in that tank are fine. That tank has a HOB (Tetra Whisper 60) with a medium to high flow that I can’t lower without it making an annoying noise. It is 77F, pH 7.4, and no significant nitrates or anything else. I also added two roobios tea bags to the water in this tank for about a day. No idea if any of that would have an effect.

I dose each tank with CO2 booster a few times a week and put in Flourish with water changes.

Any thoughts on what to do here or what’s causing this?

 

[Guppy777]

Could be the high flow in your tank, had the same problem and it didnt really take off till the flow decreased.

 

[JJun]

Do the tops of the frogbit get wet? My LFS told me to keep the tops dry as possible so they don't start rotting. Just got myself some and made a round air hose tube ring and attached some fishing line to keep them from getting into the water flow of my filter...

 

[TClare]

I have often read that the leaves of floating plants should not get wet. This seems illogical to me as it definitely rains where they come from naturally! But perhaps if they are constantly wet with no evaporation (eg in a tank with a lid and a lot of condensation) this could harm them. But I think the most likely explanation is the higher flow rate in the bigger tank. I haven't actually had frogbit, but I have water lettuce in all my tanks, one tank has more surface movement than the others and in that tank it lives but does not grow as big or spread as quickly as in the other tanks. I am not sure , but making a corral out of airline tube might help to keep it one place and let it get going. When it has grown some more it tends to hold itself together and the flow not affect it so much, the corral can then be removed.

 

[Seasoldier]

What's your lighting like in the two tanks? I had water lettuce in my tank with four T5 tubes for lighting & it just burnt & killed them, now I have an LED system & they're just fine.

 

[JustAFishServant]

I have often read that the leaves of floating plants should not get wet. This seems illogical to me as it definitely rains where they come from naturally! But perhaps if they are constantly wet with no evaporation (eg in a tank with a lid and a lot of condensation) this could harm them.

I think you're right. But I don't even think it's what little evaporation produced that kills the plants. I think it's high general humidity.

I have 2 tanks with salvinia, for example. Both have lids (1 is a 5 gallon with a heater, the other is a 2 gallon lidded bin, no heater.) The salvinia in the 5 gal aren't thriving, but the stuff in the lidded bin are; so much so that I constantly have to sell some off, otherwise they choke each other out.

Of course, it would make sense that the 5 gal has more evaporation and, therefore, humidity, since it's heated. The lid isn't completely closed (it has a hole that I covered with plastic wrap,) but the bin has NO openings at all.

Maybe it's a combination of the flow and humidity?

 

[Zer0]

I have seen frogbits die from having too many nutrients.
I would skip the co2 and just add the flourish once per week.

 

[ruud]

Frogbit and CO2....

Not sure what the size of your hand are. The leaves don't look large and you mention colors turning yellow.

Sound like a nitrogen and / or potassium deficiency. The two main plant minerals.

Edit: I didn't read your whole text (shame on me); you mention no significant nitrates yourself...

But don't underestimate potassium, in general.