Guide to Starting and Maintaining a Saltwater Aquarium

The Ultimate Guide to Starting and Maintaining a Saltwater Aquarium from

Great Lakes Corals

Introduction

Starting a saltwater aquarium is one of the most rewarding hobbies, but it requires planning, patience, and knowledge. This guide will provide a deep dive into everything you need to know, from selecting the right tank to maintaining a thriving marine ecosystem.

1. Choosing the Right Tank

Tank Size Matters

Many beginners assume a smaller tank is easier to manage, but larger tanks offer more stability and are less prone to sudden parameter swings.

Challenges of Small Tanks (Under 30 Gallons):

More difficult to dose – Small changes in additives have a larger impact.
Rapid evaporation – Can cause salinity swings.
Limited stocking options – Hard to find small herbivores to control algae.

Best Tank Sizes for Beginners:

40-125 gallons – Stable water parameters, flexible stocking options. More expensive start up. 6’ Tanks more appropriate for Tangs and other grazers than 4’.
Nano tanks (10-30 gallons) – Require frequent maintenance, only suitable for small fish and inverts. Cheaper water and easier water changes.

Glass vs. Acrylic Tanks

Glass Tanks – Scratch-resistant, heavier, more durable.
Acrylic Tanks – Lighter, clearer, but scratches easily.

Reef-Ready vs. Standard Tanks

Reef-Ready Tanks – Pre-drilled for sumps and overflow filtration. Best choice.
Standard Tanks – Require external filtration or modifications. HOB and canisters are not the most efficient and require more maintenance. HOB with surface skimmers is ideal to prevent surface films.

2. Essential Equipment

Filtration

Live Rock – The primary filtration in saltwater tanks. Use 1-4 lbs per gallon.
Sump System (Recommended) – Increases water volume, improves filtration.
Hang-On-Back (HOB) Filter – Works for small tanks but requires frequent cleaning.
Canister Filter – Useful for fish-only tanks but not ideal for reefs. Easily neglected.
Bio-media- naturally lowers nitrates and phosphates
Fleece rollers- Expensive but the most effective way to remove detritus and leftover food.

Protein Skimmer

Removes organic waste before it breaks down into ammonia.
Reduces nutrient buildup, improves water clarity and oxygenation.
Essential for reef tanks but optional for fish-only setups.

Lighting

Fish-Only Tanks: Basic LED lighting.
Reef Tanks: Full-spectrum LEDs (AI Prime, Radion, Kessil, Reefi).
Budget Option: Amazon Black Box LEDs.

Flow

Fish-Only Tanks: Basic wavemakers
Reef Tanks: Pulse and/or Random Flow wavemakers
Budget Option: Jebao brand pumps
2 or more smaller wavemakers are better than one larger.

3. Setting Up the Aquarium

Substrate Options

Shallow Sand Bed (1-2 inches): Easy to maintain, minimal detritus buildup.
Deep Sand Bed (3-4 inches): Helps with nitrate reduction, but harder to maintain. Old school. Careful stirring to release toxins.
Bare Bottom Tank: Easier to clean, prevents detritus buildup. Less Biological Filtration.

Rockwork & Biological Filtration

Live Rock vs. Dry Rock:

Live Rock: Comes with bacteria but may introduce pests.
Dry Rock: Pest-free, needs time to seed with bacteria.
Dry Rock with Live Rock to seed faster with less risks.

Aquascaping Tips:

Use 1-4 lbs of rock per gallon.(not a rule, a suggestion)
Create caves and overhangs for fish hiding spots. Important.

Water Flow & Circulation

Proper water movement is essential for maintaining a healthy saltwater aquarium, particularly for reef tanks. It ensures oxygen exchange, nutrient distribution, and waste removal, all of which contribute to the well-being of corals and fish.

Nutrient Transport: Corals rely on flow to receive essential nutrients and remove waste.

Creating the Ideal Flow for Corals

Unlike freshwater fish, corals do not thrive under constant, linear water movement. Instead, they benefit from random, pulsing, and turbulent flow patterns, which more closely resemble ocean currents.
Avoid Direct, Straight Flow: Constant blasting can stress corals and damage tissue.
Use Multiple Powerheads: Positioning powerheads at different angles creates overlapping currents.
Utilize Wave Makers: Devices such as Vortech, Nero, and Gyre pumps can create varied water motion.
By mimicking natural ocean currents, you create a dynamic environment where corals thrive, fish behave more naturally, and debris remains suspended for easier filtration.

Mixing Saltwater

Use RO/DI water in a mixing container. Add salt to water, never water to salt.
Follow the salt mix manufacturer’s instructions.
Aerate for 3-24 hours (different instructions for different brands) with a powerhead before using. Check specific gravity with a refractometer (Target: 1.025).

4. The Nitrogen Cycle & Tank Maturation

Ammonia (Highly Toxic): Should always be 0 ppm.
Nitrite (Not Toxic in Marine Systems): Converts into Nitrate.
Nitrate (Essential for Corals): Aim for 5-15 ppm.
Bottled Bacteria Products: Brightwell XLM, Dr. Tim’s One & Only.

Cycling a Tank (Fishless Method Recommended)

Add an ammonia source (pure ammonia or fish food).
Monitor ammonia, nitrite, and nitrate levels.
Wait 4-6 weeks for ammonia and nitrite to reach 0 ppm.
Add a small cleanup crew once cycle completes.

5. Adding Livestock (Slow & Steady Wins!)

Introducing fish and invertebrates gradually prevents stress, aggression, and water quality issues. Always research compatibility before purchasing.

Beginner-Friendly Fish

Clownfish – Hardy and easy to care for.
Firefish – Peaceful but jumpers (use a lid).
Blennies (Lawnmower, Midas, Tailspot) – Great algae grazers.
Royal Gramma – Colorful, semi-aggressive but manageable.

Avoid: Tangs (need large tanks), Butterflyfish (special diets), and aggressive species.

Acclimation Process

Float the bag for 15-20 minutes to match temperature.
Drip acclimate (recommended for sensitive species) – Slowly drip tank water into a bucket for 30-60 minutes. Alternately you may add a cup of water every 10-15 mins until volume had doubled.
Do NOT add store water to your tank – It may contain parasites or medications.

Stocking Tips

Add peaceful fish first, aggressive last.
Wait at least a week between new additions.
Quarantine new fish if possible.

A slow, steady approach ensures a stable, stress-free aquarium.

6. Routine Maintenance

Daily Tasks

Top off RO/DI water if no ATO is used – Evaporation causes salinity to rise, so adding fresh water daily helps maintain stability. If using an Auto Top-Off (ATO), check that it’s functioning correctly.
Check the temperature & salinity – Sudden temperature swings or salinity fluctuations can stress fish and corals. Make adjustments as needed.
Observe fish and corals for signs of stress or disease – Look for changes in behavior, color loss, fin damage, or coral retraction. Early detection can prevent major issues.
Ensure all equipment is running properly – Make sure heaters, powerheads, skimmers, and return pumps are functioning as expected.

Weekly Tasks

Test alkalinity, calcium, magnesium, nitrate, and phosphate – These parameters determine coral health and stability. Use Hanna Checkers or Salifert test kits for the most accurate results.
Clean the glass with a magnet cleaner or algae scraper – Prevents algae buildup, keeping the tank looking clear. Careful of silicone corners.
Replace or clean filter socks and mechanical filtration media – Helps remove detritus before it breaks down and contributes to nutrient buildup. Ideally, socks should get swapped every 1-3 days.
Check and empty the protein skimmer collection cup – If the skimmer is producing excess skimmate, adjust settings to avoid nutrient stripping.
Siphon detritus from low-flow areas – This prevents nutrient buildup and potential algae outbreaks.

Biweekly Tasks (Every Two Weeks)

Perform a 10-20% water change – Helps dilute excess nutrients and replenishes trace elements.
Vacuum the sand bed (if applicable) – Only if you don’t have a sufficient cleanup crew. Avoid disturbing deep sand beds too much.
Inspect powerheads and return pumps for obstructions – Snails, detritus, and algae can clog pumps, reducing flow efficiency.

Monthly Tasks

Deep clean protein skimmers and powerheads – Remove built-up calcium deposits and gunk to ensure optimal performance. (every 3-6 months or as needed)
Check and recalibrate probes (pH, salinity, temperature) – Probes drift over time and need recalibration for accurate readings.
Inspect all electrical components for salt creep or corrosion – Wipe down cords, outlets, and plugs to prevent malfunctions.
Assess coral and fish growth – Make any necessary dosing or stocking adjustments based on observed changes.

7. Algae Control & Nutrient Management

Algae growth is one of the most common challenges in a saltwater aquarium. While many assume high nutrients are the primary cause, algae can still thrive in low-nutrient systems if proper herbivores are lacking. A combination of good nutrient management and an effective cleanup crew is the best long-term solution.

Common Causes of Algae Growth

Excess Nutrients (Nitrate & Phosphate) – Elevated levels fuel algae blooms.
Inadequate Herbivores – Many tanks lack the proper snails, crabs, or fish to graze on algae before it spreads.
Too Much Light / Wrong Spectrum – Intense or improperly tuned lights can encourage unwanted algae growth.
Poor Flow & Dead Spots – Areas of low water movement allow detritus to settle, increasing nutrient levels.
Overfeeding & Uneaten Food – Excess fish food breaks down into nitrates and phosphates, fueling algae.

How to Control & Prevent Algae

1. Introduce Proper Herbivores

The best defense against algae is a well-balanced cleanup crew (CUC). Every algae type requires different grazers:

Algae Type	Best Cleanup Crew Members
Green Film Algae	Trochus, Astrea, Nerite Snails
Hair Algae	Emerald Crabs, Turbo Snails, Lawnmower Blenny
Diatoms	Cerith Snails, Nassarius Snails
Cyanobacteria	Increased flow, Chemiclean (if necessary)
Bubble Algae	Emerald Crabs, Manual Removal
Turf Algae	Tangs (in larger tanks), Urchins

A strong cleanup crew can prevent algae from taking hold, reducing the need for chemical treatments or manual removal.

2. Manage Nutrient Levels (Nitrate & Phosphate)

Target nutrient levels:

Nitrate (NO₃): 5-15 ppm (Avoid 0 ppm—corals need some nutrients!)
Phosphate (PO₄): 0.02-0.1 ppm

How to Reduce High Nutrients:

Regular water changes (10-20% biweekly) help dilute excess nutrients.
Reduce feeding & remove uneaten food before it decomposes.
Use macroalgae (Chaetomorpha) in a refugium to absorb excess nutrients.
Install a protein skimmer to remove dissolved organics before they break down.
Run phosphate-removal media (GFO, RowaPhos, Lanthanum Chloride) if phosphate levels are too high.

3. Adjust Lighting & Photoperiod

If algae growth is excessive, check how long and how intense your lights are running:

Reef Tanks: 8-10 hours per day is usually sufficient.
Fish-Only Tanks: Lights should only be on when viewing the tank—excessive lighting promotes algae.
No Corals? Turn lights off for a few days to help starve algae of its energy source.

8. Understanding Water Chemistry (Deep Dive)

Parameter	Ideal Range
Alkalinity	8-12 dKH
Calcium	400-450 ppm
Magnesium	1250-1350 ppm
Nitrate	5-15 ppm
Phosphate	0.02-0.1 ppm
pH	7.8-8.4
Salinity	1.025 SG (35ppt)

Why Stability Matters

Fish and corals thrive in stable environments. Sudden fluctuations in pH, salinity, alkalinity, or other parameters can stress marine life and lead to disease or death.
Maintaining proper chemistry reduces algae outbreaks, coral bleaching, and fish illness.
Regular testing allows early detection of potential issues before they become serious problems.

Ideal Water Parameters for a Reef Tank ---à

9. Types of Saltwater Aquarium Setups

Fish-Only with Live Rock (FOWLR) – Adds natural filtration.
Reef Tank (Softies, LPS, SPS) – Increasing difficulty levels.
Predatory Tanks – Keeping larger, aggressive fish

10. Salt Mixes: Choosing the Right One

Choosing the right salt mix is crucial for maintaining stable water chemistry. Different formulations cater to fish-only tanks and reef systems, so selecting the right one depends on your livestock needs.

Reef Salt vs. Standard Marine Salt

Standard Marine Salt – Suitable for fish-only and FOWLR tanks, containing basic elements for marine life.
Reef Salt – Formulated with higher calcium, alkalinity, and magnesium to support coral growth.

Popular Salt Brands

Instant Ocean – Budget-friendly, great for fish-only tanks.
Reef Crystals – Enhanced with extra calcium and trace elements.
Tropic Marin Pro Reef – High-quality, balanced for reef systems.
Red Sea Coral Pro – Designed for SPS/LPS corals, mixes with elevated parameters.
Fritz RPM – Pre-mixed for stable reef conditions.
Brightwell NeoMarine – Highly refined mix with consistent trace element balance.

11. Stocking Your Tank (Step-by-Step Plan)

Adding livestock to your saltwater aquarium requires careful planning to ensure a stable environment for all inhabitants. Introducing too many fish at once or adding incompatible species can lead to stress, aggression, or water quality issues.

Stocking Order: The Safe Approach

Start with a Cleanup Crew (CUC) – Includes snails, hermit crabs, and shrimp to help manage algae and detritus.
Add Hardy, Peaceful Fish First – Clownfish, Firefish, Blennies, and Gobies are excellent beginner choices.
Introduce Semi-Aggressive Species Later – Dwarf Angelfish, Tangs, and Wrasses should be added last to minimize territorial disputes.
Corals & Invertebrates(anemones) – Introduce after parameters have stabilized (typically after 3-6 months).

Tank Capacity & Overcrowding

Rather than using a strict inches-per-gallon rule, consider each fish’s adult size, aggression level, and the tank’s nutrient capacity. Monitor nitrate and phosphate to ensure the bio-load isn’t overwhelming your filtration. If levels rise too quickly after adding a new fish, you may need to reduce feeding, improve filtration, or reconsider your stocking plan.

Beginner-Friendly Fish & Their Requirements

Fish	Minimum Tank Size	Temperament	Notes
Clownfish	20 gallons	Peaceful(sometimes)	Hardy, easy to feed
Royal Gramma	30 gallons	Semi-aggressive	Territorial but manageable
Firefish	20 gallons	Peaceful	Jumpers—requires a lid
Blennies (Lawnmower, Midas)	40 gallons	Peaceful	Great algae grazers, lots of personality
Gobies	20 gallons	Peaceful	Often pair with pistol shrimp

Research Each Purchase. This is your job, not the stores!

Aggression: Some species can become territorial as they mature.
Tank Size: Many fish sold as juveniles will need larger accommodation.
Diet & Compatibility: Ensure every new fish can coexist peacefully and has appropriate food.

12. Common Equipment Mistakes (And How to Avoid Them!)

Beginners often make mistakes when selecting and using equipment for their saltwater aquariums. Understanding common pitfalls can help you save money, avoid stress, and create a more stable environment.

1. Choosing the Wrong Light

Fish-Only Tanks: Any basic LED or fluorescent light works.
Reef Tanks: Require full-spectrum LEDs with proper PAR levels.
Mistake: Buying low-quality "budget" LEDs that don’t truly support coral growth.
Solution: Invest in reputable brands like AI Prime, Kessil, or Radion, etc.

2. Over- or Under-Skimming

Protein skimmers help maintain low nutrients by removing organic waste.
Mistake: Choosing a skimmer too small or large for your system.
Solution: Select a skimmer rated for 0.75x-1.75x your tank volume. Sometimes slightly smaller will skim better but too big doesn’t skim properly.

3. Not Using an ATO (Auto Top-Off)

Mistake: Manually adding freshwater daily to compensate for evaporation.
Solution: Install an ATO system to maintain stable salinity levels automatically.

4. Incorrect Flow Placement

Mistake: Placing powerheads so that they create dead zones. Using wavemakers without a pulse or randomized flow setting.
Solution: Ensure flow is evenly distributed, avoiding stagnant areas.
Surface Agitation: the surface should never be still.

5. Forgetting Backup Power Solutions

Mistake: No plan for power outages.
Solution: Use battery-powered air pumps or a generator to keep oxygen levels stable. Flow is more important than Heat if you must choose.

6. Using Low-Quality Test Kits

Mistake: Relying on API test kits, which can be inaccurate.
Solution: Use reliable brands like Hanna Checkers and Salifert for accurate testing.

13. How to Quarantine Fish & Corals

Quarantining new fish and corals is a crucial step in preventing diseases and pests from entering your main display tank. Proper quarantine procedures save you from future headaches and costly losses.

Why Quarantine?

Prevents disease introduction (Ich, Velvet, Brook, Uronema).
Reduces stress on fish before adding them to a competitive environment.
Allows time for observation and treatment if necessary.

Fish Quarantine Process (2-6 Weeks Recommended)

Setup a Quarantine Tank (QT) – Bare-bottom tank with a sponge filter, heater, and aeration.
Acclimate & Observe – Watch for signs of disease for at least a week.
Medications & Treatments

Copper (Cupramine): Treats Ich & Velvet.
Formalin: Treats Brook & Uronema.
Prazipro: Treats internal parasites.

Monitor & Feed Properly – Offer high-quality frozen foods to strengthen immune systems. Remove any uneaten food.
Transfer to Display Tank – After a clean bill of health, move fish carefully to avoid stress.

Coral Quarantine & Dipping

Dip corals in a coral-safe dip (Revive, Bayer, or Coral RX) to remove pests.
(optional) Observe in a separate system for 2-4 weeks before adding to the main display.
Watch for Aiptasia, flatworms, nudibranchs, or brown jelly disease.

14. How to Prevent and Treat Diseases in Fish

Saltwater fish are susceptible to a variety of diseases, many of which can be fatal if not caught early. Prevention is always better than treatment, and proper quarantine and observation can reduce the risk of introducing pathogens into your main display tank.

Common Fish Diseases & Treatments	Symptoms	Treatment
Marine Ich (Cryptocaryon irritans)	White spots, flashing, rapid breathing	Copper-based treatment (copper power, Cupramine), tank transfer method (TTM)
Marine Velvet (Amyloodinium)	Dusty gold coating, rapid gill movement, lethargy	Copper treatment (Chloroquine phosphate, Copper power, Cupramine), freshwater dips
Brooklynella (Clownfish Disease)	Mucous sloughing, rapid respiration	Formalin baths, metroplex treatment
Uronema (Common in wrasses)	Red sores, rapid deterioration	Metronidazole, tank sterilization

Best Practices for Disease Prevention

Always quarantine new fish for 4-6 weeks before adding them to your display.
Avoid cross-contamination by using separate nets and tools for quarantine and display tanks.
Maintain stable water parameters to reduce stress, which can weaken fish immune systems.
Feed nutrient-rich diets with supplements like Selcon to boost immunity.

15. The Best Cleanup Crew for Your Tank

A healthy saltwater aquarium needs an effective cleanup crew (CUC) to help control algae, consume detritus, and maintain overall tank cleanliness. The best cleanup crew is diverse, with different species serving specific roles.

Best Cleanup Crew Members

Species	Role
Trochus Snails	Algae control, can flip themselves over
Nassarius Snails	Scavengers, keep sandbed aerated
Cerith Snails	Algae grazers, burrow into sand
Emerald Crabs	Eat bubble algae, general scavengers
Cleaner Shrimp	Pick parasites off fish
Brittle Starfish	Scavenge uneaten food and detritus

How to Build a Balanced Cleanup Crew

Match the cleanup crew size to your tank’s needs. Too many scavengers can lead to starvation.
Avoid overstocking hermit crabs as they can prey on snails for their shells.
Observe algae growth and detritus buildup to decide if more members should be added.

16. Advanced Water Testing & ICP Analysis

Beyond standard test kits, advanced testing methods like ICP (Inductively Coupled Plasma) analysis can provide a deeper understanding of your tank’s water chemistry. ICP testing can detect trace elements and contaminants that typical home test kits miss.

Why Use ICP Testing?

Identifies trace element deficiencies (e.g., iodine, potassium, strontium) affecting coral health.
Detects harmful contaminants like heavy metals (copper, lead, zinc) that may leach from equipment.
Provides precise measurements of calcium, magnesium, alkalinity, and other major parameters.

How to Interpret ICP Test Results

Low trace elements? Supplement with targeted additives (Fauna Marin, Triton).
Heavy metal contamination? Use activated carbon and poly-filter pads to remove toxins.
Nutrient imbalances? Adjust feeding, filtration, and water changes as needed.

17. Automating Your Tank

Automation can make maintaining a saltwater aquarium much easier and reduce human error. Key areas that can be automated include water top-offs, dosing, and monitoring.

Key Automation Tools

Equipment	Purpose
Auto Top-Off (ATO) System	Maintains stable salinity by replacing evaporated water
Dosing Pumps	Automatically adds calcium, alkalinity, and magnesium
pH & Temperature Controllers	Ensures stable parameters and prevents overheating
Auto Water Change Systems	Gradually replaces water to maintain stable chemistry

Benefits of Automation

Reduces daily maintenance and human error.
Maintains stability, crucial for sensitive corals.
Allows remote monitoring via aquarium controllers (Apex, Hydros).

18. Setting Up a Refugium (Algae & Copepods)

A refugium is a separate area in your system designed to grow beneficial macroalgae, provide a haven for copepods, and enhance nutrient export.

Benefits of a Refugium

Reduces nitrates and phosphates by growing macroalgae like Chaetomorpha.
Increases copepod populations for natural fish food (Mandarins, Wrasses).
Improves pH stability by running a reverse light cycle to balance CO₂ levels.

How to Set Up a Refugium

Choose a section in your sump or use a dedicated refugium tank.
Add macroalgae (Chaeto, Caulerpa) and provide a proper refugium light.
Use a fine sandbed(optional) and live rock rubble to encourage copepod populations.
Ensure gentle flow to avoid disturbing growing macroalgae.

19. Understanding & Controlling Nutrients

Maintaining the right levels of nitrates and phosphates is essential for a healthy reef tank. Too much leads to algae problems, while too little can starve corals of nutrients.

How to Lower High Nutrients

Increase water changes (20% every 2 weeks).
Use macroalgae in a refugium to naturally absorb excess nutrients.
Install a protein skimmer to remove organic waste before it breaks down.
Consider carbon dosing (NOPOX, vinegar, vodka) to promote beneficial bacteria growth.

Why Corals Need Some Nitrate & Phosphate

Nitrate: Levels between 5-15 ppm help fuel coral growth.
Phosphate: Levels around 0.02-0.1 ppm promote coloration and health. 0 can cause dinos and cyano issues
Too low nutrients ("ultra-low nutrient systems") can lead to coral bleaching and starvation.

20. The Best Beginner Corals (And Which to Avoid!)

Corals vary in difficulty, and some are much easier to care for than others. Choosing beginner-friendly corals ensures a successful reef-keeping experience.

Best Beginner Corals

Soft Corals: Zoanthids, Mushrooms, Green Star Polyps (GSP)
LPS Corals: Hammer, Frogspawn, Candy Cane
Hardy SPS Corals: Montipora, Birdsnest

Corals to Avoid as a Beginner

Goniopora (Flowerpot Coral) – Difficult to keep long-term.
Acropora (SPS Coral) – Requires stable parameters, strong flow, and high light.
Torch Corals – Can be aggressive and prone to Brown Jelly Disease.

21. The True Cost of a Saltwater Aquarium

Expense	Estimated Cost
Tank & Stand	$300-$3,000
Lighting	$200-$1,500
Filtration (Skimmer, Sump, Pumps)	$300-$2,000
Rock & Sand	$200-$600
Fish & Corals	$100-$2,000+
Ongoing Maintenance	$50-$200 per month

Owning a saltwater aquarium is a significant investment. Understanding costs can help set realistic expectations. Estimated Costs

Being financially prepared helps prevent cutting corners that could lead to tank failure.

22. How to Succeed Long-Term in the Hobby

Building a successful saltwater aquarium requires patience, consistency, and a willingness to learn. Here are some key tips for long-term success:

Regular Maintenance Schedule: Consistency in water changes, testing, and cleaning prevents major issues from creeping up.
Stable Parameters: Rapid swings in salinity, alkalinity, or temperature stress livestock.
Research & Ongoing Education: The saltwater hobby is constantly evolving—keep reading, watching videos, and learning.
Join the Community: Forums, local clubs, and social media groups offer support, troubleshooting advice, and camaraderie.
Invest in Quality Equipment: Buying cheap gear often leads to expensive upgrades down the road.
Be Patient: Nothing good happens fast in a reef tank—rushing can lead to costly mistakes.

23. What to Do in an Emergency

Despite best efforts, emergencies can happen. Power outages, equipment failures, and unexpected tank leaks can threaten your livestock.

Emergency Preparedness

Battery-powered air pumps to keep oxygen levels stable during power outages.
Have spare heaters and pumps on hand for quick replacements.
Leak-detection sensors can alert you to tank or plumbing issues.

Handling a Crisis

Stay Calm: Rash decisions often make things worse.
Address Oxygen & Temperature First: Low oxygen is a quick killer—use battery air pumps. If you cant do both, flow is more important than heat.
Fix the Root Cause: Whether it’s a broken heater or clogged filter, resolve the primary issue.
Perform Partial Water Changes if Needed: This can help restore water quality.