Do I need my second filter?

[PineSong]

This is my 20g long. Stocking at the moment is:

10 platies, 3 mollies,10 male guppies/endlers,1 otocinclus, 1 mystery snail. The substrate is @ 1.5 inches deep and you can see the volume of plants in the photo below. Duckweed covers the top of the tank faster than I can remove it; not sure if that's visible.

Thr tank has a sponge filter (co-op size medium) and an Aquaclear 20. 

For a couple of reasons, I'd like to remove the HOB filter if I can safely do that. Based on my past experience of having a planted tank with no filter at all, I suspect I can safely run this tank without the HOB. Buuuut this tank is more heavily stocked than my old one was and I'd like to be cautious so I thought I'd ask what others' experience would say.

[HH Morant]

I think you just have to try it, monitor the water quality, and see what happens. There are too many variables to make a prediction. How much do you feed? How good is the bacteria in the sponge filter? I don't know how to predict how much the plants will help (they look great). I guess aquarium maintenance is another variable.

I have never had an aquarium with just a sponge filter. Generally, my approach is to aim for over-filtration.

[PineSong]

On 11/20/2021 at 9:25 PM, HH Morant said:

I think you just have to try it, monitor the water quality, and see what happens. 

I have never had an aquarium with just a sponge filter. Generally, my approach is to aim for over-filtration.

I started out as a fishkeeper with goldfish, so I have a long history of over-filtration, too. It's what I am used to--filter like you're housing orca because you only have 55 gallons for 3 goldfish.

I think I'm a "medium" feeder. I only have 2-3 ramshorns and no noticeable bladder snails in this tank despite it having had the same plant sources as my fry tanks which have dozens of snails because of all the food there.

I think I'm going to try it. 

[Streetwise]

Your plants are epic, and your tank looks really nice. I’m sure you would be fine with just a sponge.

[PineSong]

Update: one week later. Still zero Nitritres and Nitrates, but a very noticeable change is in the distribution of duckweed.

Instead of being carried by the current and then covering the surface in a clump around the plants that reach the top of the tank, it is spread out across the whole surface. I've removed what looked like half of it twice this week, yet the entire surface is covered again this morning. Looks like I'll need to upgrade my removal methods.

Fish seem equally happy as they now have more open glass for begging on the back side of the tank when they see me in the kitchen.

[PineSong]

Four week update: This morning's water test showed 25ppm nitrAte; last water change was a week ago. This is the only change in the parameters over the course of 4 weeks without the HOB.

The plants are growing well, maybe better than ever. Tackling the duckweed will be my project for mid week. Daily removal of all that I can net out on the back half while they eat in the front half has accomplished exactly nothing.

[Guppysnail]

That’s awesome. Interesting that is seems the filter bacteria were actually stealing needed food from your plants. That tank looks phenomenal! Are all the wavy leaves floating from a sword or something else?  I love that look. 

Edited December 12, 2021 by Guppysnail

[PineSong]

On 12/12/2021 at 10:09 AM, Guppysnail said:

That’s awesome. Interesting that is seems the filter bacteria were actually stealing needed food from your plants. That tank looks phenomenal! Are all the wavy leaves floating from a sword or something else?  I love that look. 

Thank you, Guppysnail. I am really happy with it. It may be that the filter from the HOB was using up nutrients, or I think I read that it could also be that the surface agitation from the HOB was releasing C02 from the water column into the air. Additionally, because I'm just futzing around and not doing real science, at some point in the past 4 weeks I switched from giving my whole Easy Green dose once a week to dosing half twice a week, and that may have made an impact? Not sure.

Those wavy leaves are from an aponogeton (ulvaceous, I think) that I got in a bag of mixed "betta bulbs" at Petco.  In my more recent purchase of the same product, the aponogeton that grew is another variety, not as wavy. There's a thread about this aponogeton in the Plants section if you want more info about how it has grown for people before you try it. I had no idea a "betta bulb" would get this big 🙂