Best aquarium by size - tank buying guides

11 tank-size buying guides covering the most common aquarium sizes from 5-gallon nano to 220-gallon show display. Each guide includes top picks across budget tiers, dimensions, filled weight, livestock compatibility, and full setup essentials.

Best 5-gallon aquariumFor betta or shrimp nano. 16"×8"×10", ~50 lbs filled.3 picks · full setup guideBest 10-gallon aquariumFor planted nano or community starter. 20"×10"×12", ~100 lbs filled.3 picks · full setup guideBest 20-gallon aquariumFor community freshwater or nano reef. 24"×12"×16" (Long: 30"×12"×12"), ~200 lbs filled.4 picks · full setup guideBest 29-gallon aquariumFor community freshwater. 30"×12"×18", ~290 lbs filled.3 picks · full setup guideBest 40-gallon breeder aquariumFor planted or breeding setup or nano reef. 36"×18"×16", ~400 lbs filled.3 picks · full setup guideBest 55-gallon aquariumFor large community freshwater or smaller cichlid. 48"×13"×21", ~550 lbs filled.3 picks · full setup guideBest 75-gallon aquariumFor mixed reef or large freshwater. 48"×18"×21", ~750 lbs filled.4 picks · full setup guideBest 90-gallon aquariumFor large community or mbuna or mixed reef. 48"×18"×24" or 36"×18"×30", ~900 lbs filled.3 picks · full setup guideBest 125-gallon aquariumFor large reef or oddball freshwater. 72"×18"×21", ~1250 lbs filled.3 picks · full setup guideBest 180-gallon aquariumFor large reef + full tang stocking, large oddball setup. 72"×24"×24", ~1800 lbs filled.3 picks · full setup guideBest 220-gallon aquariumFor show-tier reef or display-quality oddball. 72"×24"×30" or 84"×24"×24", ~2200 lbs filled.3 picks · full setup guide

Choosing aquarium equipment that lasts

Equipment is where you allocate budget for stability. The cheapest pump runs hot + dies in 18 months; a quality pump runs cool for 8-10 years. The math on equipment is dramatic: a $400 quality canister filter beats four $100 cheap canisters across a decade, plus saves you the maintenance headaches + livestock losses from failures.

Three principles for equipment selection: 1) Oversize for the job - rated GPH is always inflated by 30-40%; size everything for the worst-case load. 2) Brand-name over no-name - established brands (Eheim, Sicce, EcoTech, Tunze, Hydor, Reef Octopus, Fluval) have parts available + service centers. 3) Plan for redundancy - 2 smaller heaters beat 1 large one (if one sticks, the other still works + the controller catches it).

For purchase planning, use our equipment budget builder, heater wattage calculator, protein skimmer sizing, and filter turnover calculator.

Frequently asked questions

Should I buy used equipment? Yes for tanks + stands + plumbing (inspect for cracks). No for pumps + heaters + UV bulbs (unknown remaining life). Maybe for skimmers if you can clean + verify.

How long should equipment last? Quality heaters: 2-3 years (replace preventively). Pumps: 5-10 years. Skimmers: 10+ years (replace pump every 3-5). Filters: 10+ years (rebuild seals every 3-5). LED fixtures: 5-7 years.

Wattage vs gallons rule for heaters? 3-5W per gallon for cool rooms, 1-3W per gallon for warm rooms. Use 2x smaller heaters for redundancy + safety. See heater wattage calculator.

Sump or HOB filter? HOB for tanks under 40g (cheap, easy). Canister or sump for 40g+ (better filtration capacity, room for media customization). Sump required for 75g+ reef.

What about controllers (Apex, Inkbird)? Inkbird ($30-50) for any tank - protects from heater failure. Apex ($400-800) for SPS reef + dosing automation + Wi-Fi alerts. Worth every penny.

Related resources

All equipment · Best aquarium by size · Equipment comparisons · Brand vs brand · Equipment budget builder · Calculator library (29) · DIY projects · Apex controller glossary