Substrate recommendation for a 20-gallon planted tank?

Hi, everyone;
I am setting up a new 20-gallon (long, if that matters) and want to go the low-tech planted route — with no CO2 injection, just decent lighting and maybe with root tabs/liquid ferts as needed. Planning on easy stuff to start: anubias, java fern, crypts, maybe some dwarf sag or vallisneria if I get ambitious.
I keep going back and forth between a few options and could use some real-world input:

• Plain gravel + root tabs
• Something like Fluval Stratum or ADA Amazonia (worried these are more "high-tech" oriented and maybe overkill/finicky for a low-tech setup)
• Sand cap over an active substrate
• Plain black sand with root tabs for the heavier feeders

Budget isn't unlimited, not buy something that's wasted on a low-tech setup, but I also don't want plants struggling because I went too cheap.

For anyone running low-tech planted tanks — what's actually worked well for you long-term? Any substrates you regret buying? Also curious if depth matters much for root feeders like sword or crypts in a low-tech setup.

Thanks!!

No expert by any means, I have three planted tanks that have all been running for 2+ years. 1 with fluval stratum. Honestly don't care for it, seems as this tank is always dusty ( like the stratum is breaking down ). The plant leaves always have a dusting on them. I do have a breeding colony of Cory's in this tank so that might be why. It's expensive but plants seemed to do well from the start. Have one tank with eco complete, plants do well but it took about 8 months. Have noticed my Cory's in this tank lost their barbells (may be to sharp?). Last tank has black diamond blasting sand. Plants did well after about a year and it's cheap. My Cory's love it. Haven't really used a lot of root tabs in any of my tanks. What I have experienced, good luck with your decision.

If you'd like a natural sand look, I would recommend buying a bag of pool filter sand from a swimming pool supply store. It's inexpensive, and isn't likely to require rinsing.

I have seen reports on this and other similar forums that pool filter sand can be purchased for a little less money at the big box home improvement stores, but they have also said those need rinsing. I have used two different brands from pool supply stores. One of them didn't cloud the water at all, and the other one only made the water slightly cloudy, and it was cleared up by the next morning.

If you want black sand, I have had good luck with Black Diamond sandblasting sand (I bought mine at Tractor Supply, if I remember correctly). I have been happy with it, but it requires quite a bit of rinsing.

A 20 gallon high tank requires a minimum of 20# of sand or gravel. For a 20 gallon long like you plan, you will need a minimum of 30# due to the larger bottom area.

You can uuse sand or gravel as long as the gravel is not too large. I like using coated gravel as you have less issue with debris. If you use gravel and plan to have cory cats, be sure the gravel does not have sharp edges that will irritate the mouths of your catfish. That is another reason I like coated gravel.

Please remember that anubias and ferns have rhyzomes that cannot be burried in the substrate. Use super glue or thread to adhere the rhyzomes to a rock or piece of driftwod so the rhyzome is about 1/2" above the substrate. The rhyzome will soon send roots down into the substrate and new leaves upward. These plants do well in a low tech tank.

Plants without rhyzomes should be planted with the roots in the substrate and the crown at the top of the substrate. Stem plants can be rooted or left floating.

I've grown crypys, vals and anubius with Black Diamond Blasting Sand. Around $10 for 50#. It needs to be rinsed.

Something like Fluval Stratum or ADA Amazonia (worried these are more "high-tech" oriented and maybe overkill/finicky for a low-tech setup)

Click to expand...

This is often argued, but just as often high-tech setups rely mostly or solely on water-column dosing, while low-tech setups are advised to use a nutrient-rich (or carbon-rich) substrate. Walstad tanks and aquaponics work on basis of fish waste only.

I've grown creepers like Hemianthus callitrichoides Cuba (dwarf baby tears) in plain sand and currently have Micranthemum Monte Carlo creeping in plain sand.

Hence, plain sand seems fine. In case of doubt, add a root tab below a plant.

Thickness is hardly important. Crypts and swords also grow floating or in a basket. In shallow substrate, the roots run laterally along the bottom. And if roots breach through the substrate, add more sand later and pull the plant somewhat up. Don't overthink.

This is my low-tech aquarium uses hth pool filter sand after 2 or so years:




Terrible stuff makes the aquarium look like a bunch of weeds took over.

This one did a little better:

There are many ways to get a nice planted tank without breaking the bank. My suggestion is to pick a style/method, learn all you can about it, then implement. One of the Youtubers I liked a lot is MD Fish Tanks he has videos on a variety of methods for setting up planted tanks. Everything from low tech to very high tech systems.

I've used the soil in mesh bags capped by sand in the two tanks below with decent success. One thing I do recommend is a good floating plant like Salvinia Minima. They are easy to grow and help export excess nutrients. I know I remove a couple handfuls from each of these tanks every couple of weeks. I don't really try growing any, what I would consider, difficult plants.

In the two aquariums below I've used bags of soil capped with sand. In the first I keep Angelfish, Congo Tetras, Rummy nose Tetras, Khuli Loaches, Panda Garas, and a variety of snails. The second is a smaller tank with Harlequin Rasboras, a variety of Corydoras, a dwarf Gourami, a colony of cherry shrimp, a couple of Amano shrimp, and snails. Both tanks have critters that like the sand bottoms.



I have other tanks, my two shrimp tanks, where I used soil (Fluval Stratum) without a sand cap. It worked out fine but it did take longer to get my parameters to settle down.

In my 5-Gallon betta tank, below, I used black sand with some root tabs.