Most aquarium problems don't materialize overnight, but develop slowly over time, and your tank has been warning you from early on. Here are some of the more common signals aquariums send forth and what they mean.
Microfauna bloom
- Tiny white worms or dots crawling on aquarium glass, an increase of microscopic life that appears when the tank has more food than it needs
- These tiny organisms like planaria or detritus worms feed on uneaten fish food, algae, and organic waste
- They are not dangerous by themselves, but are the tank's way of saying there's too much waste, too much feeding, or inadequate maintenance
- Micrifauna are always present in a healthy aquarium, but when something gets out of balance, they can reproduce fast
- Overfeeding of fish is a common cause, and the tank is simply reacting to the nutrient boost
- The best way to address this warning is to just reduce feeding and give the tank a week or two, and the microfauna will naturally balance themselves out
The water smells bad
- A healthy aquarium should smell earthy, like a forest after rain
- Bad smelling water is a red flag that demands immediate action
- There's too much organic waste breaking down, the aquarium is simply dirty and foul
- It comes from excess proteins and organics decomposing faster than your filtration or beneficial bacteria can handle
- It could be trapped debris under hardscape or a deceased fish hidden behind plants, or simple overfeeding that's quietly polluting the water column
- Smell is often one of the first signs of a tank losing balance, even before ammonia spikes or algae appear
- Easy to fix once you know what to look for
- Start by checking substrate, waste buildup can cause bad odors as anaerobic bacteria produce hydrogen sulfide, remove excess
substrate waste with vacuum or siphon
- Next, rinse out filter media gently in aquarium water (don't harm the good bacteria colony), for trapped detritus inside filters can produce bad smells
- Finally, cut back on feeding for a few days to let beneficial bacteria catch up with their work
- If the smell lingers even after these steps, do a few small water changes instead of one big one to avoid shocking the system
- The smell should fade as the tank's ecosystem returns to balance
Cloudy water
- This sign often points to bacterial imbalance, beneficial bacteria are multiplying faster than usual because something has upset the balance
- May happen after tank is too deeply cleaned, too many good bacteria cleaned out, and nitrogen recycling results
- Increased feeding, more organic waste boosts the nitrogen cycling with bacteria multiplying
- The water turns milky because the bacteria are still floating around, looking for surfaces to settle on, like substrate, plants or filter media
- It may look bad, but it's just the aquarium adjusting to a population/nutrient shift
- Refrain from more deep cleaning or large water changes, that just resets the cycle yet again, and can start the bloom all over again
- Instead, make sure the filter is flowing well, reduce feeding, and give the tank time to stabilize
- Cloudy water with a green or brown tinge is usually due to a phytoplankton bloom
- Typically appears when high nutrient levels and excessive light duration or intensity conditions are met
- May also appear after massive plant trimming
- Work on balancing nutrients, light, and CO2
- Apply steps for planktonic algae control, and follow healthy trimming guidance
Fish gasping at the surface
- Nearly always an oxygen problem, fish breathe oxygen dissolved in the water, when that level drops, the only place for oxygen exchange to happen is at the surface
- Make sure filter flow is good, and the airstone is providing sufficient movement at the surface, for it's that movement that keeps oxygen levels stable
- Water temperature can also factor in
- The warmer the water, the less oxygen it can hold
- If tank runs above 78F, consider increasing aeration or slightly lowering temperature to help fish breathe easier
- CO2 injection can also contribute to the problem, too much CO2 during the day, or leaving it on at night can push oxygen levels dangerously low
- The solution is simple, increase surface agitation, boost aeration, and double check CO2 system, monitor drop checker
Pearling
- Small levels of pearling is usually a sign that photosynthesis is working well, but excessive pearling may indicate a problem
- Pearling occurs when plants are producing more oxygen than the water column can hold, it forms bubbles on the leaves, and that's called pearling
- It happens sometimes after a water change because fresh water holds less dissolved oxygen, which forces excess oxygen out of the plants more visibly
- High lighting, with good nutrition, and CO2 injection can cause pearling by shifting photosynthesis into overdrive
- If the tank does not pearl, that's not necessarily a bad sign, it usually just means that the tank flow is good enough that the oxygen is dispersed right away instead of forming visible bubbles
- If the tank is pearling a lot, but fish are gasping for air at the surface, that usually means the CO2 levels are too high or oxygen levels are out of balance
Algae: How to avoid it, and how to deal with it when it takes over
- Prevention
- Water temperature matters, try not to go over 76F, algae thrives at higher temperatures
- Filtration helps remove organic waste before it breaks down into algae nutrients
- Over feeding, excess food and waste turn into fuel for algae (monitor nitrates)
- Lighting needs to match the plant mass, high lighting without sufficient plant mass or CO2 nearly always encourages algae
- More plants are better, high plant mass means nutrients get used and algae is out competed
- Scavengers, clean up crew, snails, shrimp, fish take care of melting leaves and other excess organic matter, preventing ammonia spikes that can trigger algae, note that algae eaters don't eliminate algae completely, but do help minimize it
- Fertilization should match plant demand, lean fertilization is usually a good idea
- CO2 injection helps by allowing plants to use light and nutrients more efficiently
- When algae gets out of control
- First identify the kind of algae
- Then deal with it accordingly, changing only one variable at a time
- Changing multiple variables at once precludes the ability to determine what change was actually effective
- The resulting imprecision can confuse the treatment causing the algae problem to drag on longer than necessary
Losing fish
- For introducing new fish use proper steps for acclimation
- Remember that fish do not live forever, and they are vulnerable to illness and old age
- In the wild, fish are subject to more danger variables like predatory fish and birds, so an aquarium is a safer environment
Losing new plants
- Almost always an issue of adaptation
- Plants adapt closely to the conditions they are grown in
- Hot house plants are usually grown emersed with leaves above the water, so when they become immersed in an aquarium, they must adapt usually, involving leaves melting and newly adapted, fresh submerged leaves growing
- Even if plants are grown immersed with leaves under water, your tank conditions are almost never identical, so in any event plants must undergo a transition period of adaptation, and that's when most losses occur
- Things to improve chances of survival and thriving
- Try to stay within the parameters common for the particular plants, plants can adapt to differences, but struggle with extremes
- Expect some melting
- Plants grown emersed always melt when submerged, and that's normal, but it's still a big energy hit
- Give plants that melt a couple weeks before plucking them out, they usually recover
- Most plants survive the melt, but some don't