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Any Tips for Setting Up a New 20G Long Tank?


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Hello, More Experienced Fish Parents. 
Long story, short — My kids got 2 female bettas a couple months ago, and it’s our first experience as fish owners.  After bad local CPS advice, emergency supply purchases, and a replacement fish, they’re currently in two 3G tanks with integrated HOB filters and preset heaters.  One tank is cycled, one is part-way there.  Want more details?  You can read my intro story here.

We just bought a 20G Long (thank you Petco sale!) with a lid.  I started getting some great suggestions on my welcome thread (linked above), but I’m always open to more.  The goal is a planted tank with hopes of a community/sorority tank someday.  Here’s where I’m at so far (probably all AOC unless specified or ya’ll tell me otherwise):

- Divider — not sure if I want black or clear.  If I want a community or sorority eventually, should I go clear with lots of tall plants to expose the females to each other now?  If not, I’m going with a Life With Pets black divider.

- Two sponge filters with air stones — should I go with medium filters since the goal is a community?

- Air pump — with AOC, will I need two?  (I know I could use a gang valve, but would one handle the lid with tightened air stones in each filter?)  How loud will that be?

- Adjustable heater

- Air valves, check valves, tubing, 

- Nicrew ClassicLED light

- I’m so overwhelmed with substrate.  I’m probably going with anubias, Java fern, crypts, dwarf sag, or any of the easy plants that don’t require CO2.  I do want some Cory’s or Kuhli’s, though.  So I don’t know what substrate to get that won’t make cycling water parameters a pain in my butt but that will be beneficial for the fishies and whatever plants.  Did I mention that I’ve never done plants before?  We’ll, I’ve just barely started hanging some pothos over their tanks now, but that doesn’t count.  

I’m 100% sure I’m overthinking it at this point…

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Honestly it sounds like you have it all under control. I have a planted tank with pea gravel from home depot. $5 for 50 pound bags. All I do for my plants is Easy Green and a cheap light. I've heard good things about Nicrew lights. Good choice. Cory's and Kuhli's enjoy sand. If that's the rout you go I like play sand (also super cheap) and it has a great look to it and is plenty soft enough for the fish. The only thing I am unsure of is how well plants will grow in play sand. I think the plants will do well in the sand because I can see biofilm growing almost 2 inches deep in the sand. I have just never tried rooting a plant in sand. 

Once you have your 20 gallon tank set up just remember to only make small changes and only make one change at a time so you can really learn what each change causes in your tank.

Like I said up top. It really sounds like you got this! Keep it up.

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Congrats on getting the 20 long--it's my absolute favorite tank! I hope you'll enjoy yours as much.

I've kept tons of bettas but never a sorority, so I can't speak to the question about whether that would impact decisions about the color of the divider.

Re: size of filter. I use a small Co-Op sponge filter in my 20L, and an airstone in the other corner for additional aeration. Since sponge filters do not actually remove any waste from the tank unless you clean them, the main function of the filter is as a place for beneficial bacteria to live.

Having a larger filter will give you more room for that, but so will driftwood, cholla, stones and substrate, plant surfaces, so size doesn't matter so much in a tank with lots of surfaces. Filter size matters much more in a bare tank being used for QT, or housing fry, or petshop tanks with just gravel and glass etc. A larger filter will hold more gunk, but all that gunk is IN your tank until you take it out.

I use the smaller filter in my 20L because the filters are an eyesore and it's easier to block the view of a smaller filter with plants.  My airpump handles both the sponge filter with adjustable airstone and the other airstone (Ziss adjustable) just fine. My pump is a Tetra Whisper 40.

I use gravel (mostly CaribSea Peace River, to be specific) in my tanks. It's a gravel but quite small and it's rounded enough for cories and kuhlis. I use some Easy root tabs under heavy root-feeding plants like swords, and Easy Green liquid in the water for the floaters and Java ferns. I'm not mentioning  Peace River to sell you on it, just to say that you can grow a ton of plants in a gravel substrate that doesn't impact your water parameters.

Here is a random shot of my 20L with a few plants including one of my favorites, Aponogeton ulvaceous, which came in a $5 or $6 bag of bulbs from the betta bulbs section at Petco.



Another super easy (maybe too easy, at least in my water) plant is corkscrew val. It's been foolproof for me in every tank. If you like the sea kelp look of it, it's a good bet for creating line of sight breaks and places for fish like otocinclus to hang out away from the hustle and bustle of the open water. Added bonus, it's super easy to pull out and replant if you want to remove it and use it in other tanks or sell it.

I think your light choice will work fine. Both of the tanks in these photos are using basic Finnex Stingray lights that are not adjustable or fancy. I covered the blue light dots with duct tape to cut down on algae growth. Lights in the 20L are on a timer for 2 five-hour periods per day with four hours off in between. The tank with corkscrew val sits in a window so only has lights on for 3 hours at night so I can see the fish in the evening. You can be successful with plants with easy substrates and easy lights 🙂 Hope you have big fun!


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That corkscrew val looks awesome @PineSong


@HappilyHabil  Sounds like you have a good inventory going to get started.  You will quickly figure out everything you need once you get started.  For plants, there are a few different types that need to be fed differently.  Some need food (fertilizer) under the roots planted in the substrate.  Others feed through the water column.  Figure out which types of plants you want to start with and what type of food they need.

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