Daily Maintenance — Observe, Check, Top Up
Daily maintenance takes under 5 minutes and is the most valuable time you spend on your aquarium. Begin by observing all fish from a seated position at the front of the tank. Count every fish — missing fish found early can be recovered, missing fish found 3 days later are often dead and decomposing, polluting the water. Look for any fish with unusual posture (listing to one side, head-down, or tucked into a corner), clamped fins, white spots on body or fins, or visible wounds. These signs spotted on day one are treatable. Spotted on day seven, they are often fatal.
Check temperature with a quick glance at the thermometer. In Cambodia's variable climate, tank temperature can rise 2-3°C during the hot season in a single day if the room heats up. A thermal shock from a 25°C to 30°C swing over 12 hours is acutely stressful and can trigger ich outbreaks in susceptible species. If temperature is rising toward the danger zone (above 29°C for most community fish), add a fan blowing across the water surface or relocate the tank temporarily from direct sunlight. A $3 clip fan is a highly cost-effective temperature management tool in Cambodia.
Top up evaporation loss with dechlorinated water. In Cambodia's dry season (November-April), evaporation from a 60L open-top tank can reach 0.5-1L per day. Failing to top up increases TDS and changes chemical parameters as minerals concentrate in the remaining water. Use a marked line on the glass or a dedicated top-up container to add the same amount daily rather than infrequent large additions that cause parameter swings. Dechlorinate with sodium thiosulfate (1 drop per litre) or use aged water left sitting in a bucket overnight in which chlorine naturally off-gasses.
- ✦Count all fish during the morning feeding — a missing fish found same-day can be located and recovered; one missing for 3 days is likely decomposing
- ✦Mark the water level with a small piece of tape on the inside glass — makes daily top-up volume assessment instant and accurate
- ✦In Cambodia's hot season, check temperature at 2 PM (hottest part of day) and add a fan if it exceeds 29°C — do not wait for fish to show heat stress before acting
Weekly Maintenance — Water Change, Algae, Pre-Filter
The weekly water change is the single most important maintenance task for community aquarium health. A 25% water change removes nitrates, dissolved organic compounds, excess minerals, and hormones that accumulate between changes, replacing them with fresh, dechlorinated water. In Cambodia where stocking density in community tanks is often high and feed frequency generous, 25-30% weekly is the standard target. Use a gravel vacuum siphon during the water change to remove organic waste from the substrate — allow the vacuum to rest in each area for 10 seconds before moving, letting particles lift before the substrate itself rises.
Algae wiping should accompany the weekly water change. Use an acrylic-safe magnetic algae scraper for the interior glass and a soft cloth for the exterior. Green spot algae on the glass requires slightly more pressure; brown diatom algae in new tanks wipes off with minimal effort. Do not remove all algae — a thin film of green algae on the back glass provides food for otocinclus and a natural look, and completely sterile bare glass is harder to maintain than glass with a controlled algae presence. Wipe front and side glass, leave the back glass lightly green.
Clean the pre-filter sponge (if fitted on the filter intake) weekly by squeezing it in a bucket of tank water — never tap water, which kills the beneficial bacteria colonising the sponge. A clean pre-filter sponge maintains flow rate and traps large organic particles before they enter the main filter, extending the period between full filter cleans. In Cambodia's heat, pre-filter sponges clog faster than in cooler climates because bacterial growth is faster at 27-28°C. A second spare pre-filter sponge in rotation allows one to be cleaned while the other maintains filter function.
- ✦Do water changes at the same time every week — consistent routine is more important than the precise percentage; the fish benefit from predictable low-disturbance periods
- ✦Squeeze pre-filter sponges in removed tank water only, never tap water — tap water kills beneficial bacteria that took weeks to establish
- ✦In Phnom Penh, let tap water sit in a bucket overnight before using for water changes — chloramine (if present) requires dechlorinator, but chlorine off-gasses naturally in 24 hours
Monthly Maintenance — Gravel Vac, Equipment, Plant Trim
Monthly maintenance goes deeper than weekly tasks. A thorough gravel vacuum covering 100% of the substrate surface removes the organic waste that weekly spot-vacuuming misses. Focus especially on areas with low water flow: behind large decorations, under driftwood, and in corners where current does not reach. Decomposing organic matter in substrate produces hydrogen sulphide gas — identifiable by a rotten egg smell when the substrate is disturbed — which is acutely toxic to fish even in small concentrations. A full monthly vacuum prevents this buildup.
Check all equipment monthly: verify the heater maintains target temperature within 1°C, inspect filter impeller for debris that reduces flow, test the flow rate of powerheads or circulation pumps, and check airline tubing and airstones for blockages. In Cambodia's dusty environment, air-driven filters and airstones clog significantly faster than in humid European conditions. Replace airstones every 2-3 months — they are cheap (under 500 KHR each in any Cambodia market) and a clogged airstone represents a complete failure of oxygenation in air-driven setups.
Monthly plant trimming maintains tank aesthetics and plant health. Fast-growing stem plants like hygrophila, hornwort, and cabomba can double in size within a month under good lighting. Trim to maintain the upper third of the tank as open swimming space. Remove any yellowing or dying leaves completely — partial removal leaves a stub that rots and creates a localised water quality problem. Replant trimmed stem cuttings by pushing 5-7 cm into the substrate — they will root within a week and grow a new plant. In Cambodia, plant trimmings have resale value at local markets where planted aquarium plants are increasingly in demand.
- ✦If you smell rotten eggs when vacuuming substrate, increase water change frequency to twice weekly until the smell disappears — anaerobic substrate gas is a fish-kill risk
- ✦Replace Cambodia aquarium airstones every 2-3 months — dust clogs them faster than in more humid climates, and reduced airflow is invisible until fish start surface gasping
- ✦Sell plant trimmings to Phnom Penh planted tank Facebook groups — hygrophila and java fern trimmings sell for 2,000-5,000 KHR per portion and offset fishkeeping costs
Quarterly Maintenance — Filter Service, Light Check, Deep Clean
Quarterly filter cleaning is one of the most mismanaged tasks in home aquariums. The most common mistake is cleaning the filter too thoroughly — rinsing all media in tap water, replacing all sponges simultaneously, and cleaning the filter housing with soap. Each of these actions destroys the beneficial bacterial colony that processes ammonia and nitrite, causing a partial or full re-cycle that can kill fish. The correct quarterly approach: rinse only one-third of the filter media in tank water, leave the rest undisturbed, and never use cleaning chemicals inside the filter.
Check all lighting equipment quarterly for performance degradation. LED panels gradually lose output over time; a 12-month-old LED at maximum setting may deliver only 80% of its initial light output. For planted tanks where light intensity directly determines plant growth rate and health, this degradation matters. Check that all LED cells are functioning and replace any unit showing dead sections. In Cambodia's humid climate, moisture ingress into non-waterproof LED units is a common failure mode — ensure all lights are rated for humid environments or are positioned to avoid condensation exposure.
Perform a deep glass clean quarterly — including the rear and side glass panels normally left with algae film. Use a razor blade or purpose-made glass scraper for persistent green spot or brown algae that the magnetic scraper cannot remove. Check the silicone seams of the aquarium for any darkening, mould growth, or separation. Small silicone issues caught quarterly are repairable; a seam failure discovered when water is leaking is an emergency. In Cambodia's climate, aquarium silicone degrades faster than in cooler climates — a 5-year-old aquarium should be inspected thoroughly for silicone condition.
- ✦Never clean more than one-third of filter media in a single session — cleaning all media simultaneously causes an ammonia spike that can kill half the tank within 48 hours
- ✦Check Cambodia aquarium silicone seams quarterly with a dry paper towel pressed to each corner — any dampness on the paper indicates seam leakage before it becomes visible pooling
- ✦Test nitrate quarterly with a test kit even if the tank looks healthy — chronically elevated nitrate (above 40 ppm) suppresses immune function and shortens fish lifespan without visible symptoms
Yearly and Cambodia Wet Season Notes
Annual maintenance includes the tasks that disrupt the tank sufficiently to warrant once-yearly scheduling only. Deep substrate cleaning — removing all decor, vacuuming the entire substrate, and rinsing the tank glass with tank water — should be done in late dry season (October, just before the rains begin) when fish are at their most robust. Replace any equipment showing wear: cracked airline tubing, corroded heater elements, failing pump impellers. Refresh fertiliser supplements for planted tanks — liquid fertilisers deplete over time even when used regularly, and root tabs in the substrate are typically exhausted after 6-8 months.
Cambodia's wet season (May-October) creates specific maintenance considerations. Monsoon rain lowers ambient temperature by 2-3°C in unheated rooms, creating a natural temperature variation that can trigger ich outbreaks in tanks housing sensitive species. The increased humidity reduces evaporation significantly, meaning less top-up is needed. Flooding risk for ground-level setups in lower-lying areas of Phnom Penh is a real consideration — elevate tanks on stands at least 60 cm from the floor level during peak wet season (August-September). Power outage frequency also increases during the wet season; have a battery-powered air pump ready for outages lasting more than 4 hours.
The annual maintenance moment is also the right time for a full system assessment: review your stocking list against actual fish health and behaviour, remove any individuals that are chronically stressed or aggressive, and update your parameter targets based on a full water test including ammonia, nitrite, nitrate, pH, GH, and TDS. Fish grow over a year — what was a reasonable stocking density at juvenile size may now be overcrowded at adult size. A yearly honest stock assessment prevents the gradual drift toward overcrowding that undermines many established community tanks in Cambodia and globally.
- ✦Time annual deep cleans for October just before Cambodia's wet season ends — fish are strongest in late rainy season after months of lower temperatures and higher humidity
- ✦Keep a battery-powered air pump charged and ready for Cambodia's wet season power outages — fish tanks suffocate within 4-6 hours in a power outage without aeration in warm water
- ✦Review your stocking list annually with adult size in mind — a community that looked reasonable at purchase becomes overcrowded as fish reach adult size over 12-18 months