Frequently Asked Questions I

By: Coral Plantations Pty Ltd

How do I maintain a marine aquarium properly?

This is an all too common question and one with no simple straightforward answer. Most aquariums suffer this problem periodically, …. So what to do?

 

A water-change may be well over-due? Generally for a large (established) tank (e.g. 500L or more) a water change about once every 3-5 weeks is adequate. For smaller aquariums or those not well stabilised (say less then 6 months old), water changes more often are suggested. Generally little and often is the best. A 10% water change as often as possible (even weekly) may be desirable, especially on the much smaller tanks.

 

Associated problems with changing water:

• Water too cold: In winter be careful not to shock the system by changing too much water with cold water.. It shocks the whole system… let your water warm up for a day or two in the sun or indoors before doing the water change. In summer do about 20-30% each change. In winter if the water is markedly colder reduce this down to about 10% maximum
• Changing the chemical parameters. If you have spent the past month or so getting your pH, KH, calcium, strontium and iodine levels just right, then you have to start again. Most water changes can dramatically lower the KH (carbonate hardness) level particularly…. So, after a water change, consider testing the water again for KH, pH, and calcium and adding chemicals accordingly. Remember that the KH generator powder is great for increasing the pH and KH levels but NOT the calcium.
   

It’s also good time to dose again with strontium and iodine & that should be done weekly.

 

Nitrate levels may be way too high? This generally means “overfeeding” The long-term build up of nitrates and other nutrients (e.g. phosphates) often occur over time and from over-feeding (especially with high nutrient foods such as frozen foods and liquid coral foods).

 

Fish can tolerate reasonable levels of nitrate but many invertebrates and corals CANNOT. For fish up to 100ppm (or more) is acceptable --but- for reef invertebrates, (including corals) less than 20ppm is essential.

 

Associated problems of high nitrate levels:

• Build-up of red or green Cyanobacteria (slime mould). These bacteria can be toxic to an aquarium and have the ability to over-take and kill your system. It also has the ability to synthesise nitrates from nitrogen gas dissolved in the water, which exacerbates the excess nitrate problem.
• Water changing for nitrate reduction can be misleading If your levels are say 100+ppm nitrate and your target is less than 20 PPM, then a 1/3 water change will only reduce the nitrate level accordingly; i.e.1/3……. therefore doing at least several water changes close together will be necessary to get the level down to acceptable levels
• Reducing the nitrate levels only solves the high nitrate level – Not the cause . The cause might be over-feeding, lack of denitrification bacteria and even high nitrate levels in your water-change or top-up water
   

The water has become too salty? Salinity creep is a common problem with marine aquariums, even though the tank may have been regularly topped up with fresh water to replace the evaporated water. Salt water collected in-shore is saltier than normal, often as high as 1.025 (optimum is around 1.022). Consequently, every time a water change is made the salinity creeps up. So, during every water change, check the salinity with a hydrometer and add additional fresh water as needed. NOTE: Allow a good time (like 30min) for the fresh and salt water to mix properly before testing each time.

 

Associated problems of water too salty:

• Fish health suffers at high salinity. Fish in particular do not do well if the salinity is too high (e.g. 1.025) and generally their health is better at slightly lower then normal salinity (reduces parasites).
• Too high salinity can kill a tank. If the salinity reaches very high levels through salinity creeping up over time, it can kill numerous organisms in the aquarium “including” the bacteria; and can “crash” the system. (too hot water can also cause this)
   

You may not be adding enough essential supplements? It is important to maintain adequate levels of calcium (and strontium) and carbonates in the water to allow natural calcification by corals and invertebrates to make their calcium carbonate skeletons. Other organisms such as the lovely pink Coralline algae and the plant Halimeda also need calcium. The addition of strontium in moderately large amounts and iodine in small quantities has also shown to be highly beneficial in a closed marine reef system.

 

Associated problems of not enough supplements:

• Low levels of carbonate and calcium are common in seawater. Because local seawater and some of the synthetic salt mixes are low in carbonate hardness and sometimes calcium, you need to test for and adjust accordingly after each water change.
• Coral growth will suffer from low levels. Some corals and even coralline algae may cease to grow and even die if the KH and calcium levels are very low for some time.
   

Your lights may not be functioning properly. This generally means not enough light or old bulbs. Light bulbs need to be of adequate intensity and the right wavelength for optimum coral growth. With time both the intensity and the wavelength change (for the worse); and increased algae growth and decreased coral growth are the end results. One of the first questions asked when increased algae growth is a problem is “how old are your bulbs”…… because after 6 month the deterioration in intensity and wavelength are noticeable and bulbs/tubes should be changed at least annually

 

Associated problems with inadequate lighting:

• Avoid sunburn. Take care when replacing old bulbs with new ones. The increased intensity is likely to be so great that if care is not taken, considerable sunburn of the coral will occur. Temporarily raising the lights – for a few weeks &/or reducing the hours for a while &/or screening the corals with fly screen all work.
   

The number of algae eater may be inadequate? This means algae growth is out of control. Excess algae growth can soon smother other (desirable) growth changing the appearance from a vibrant looking aquarium to a dull lifeless one. This change is gradual and is usually noted by someone who hasn’t seen your aquarium for a while. Take heed. IF action isn’t taken quickly the set-up can quickly pass to a point of almost non-return.

 

This is usually caused by a combination of problems including excess nitrates, old lights and death of algae-eaters such as snails/shells, hermit crabs and maybe even a few algae eating fish.

 

Check out the web site for algae eaters

 

Associated problems with inadequate algae eaters

• Adding more algae eaters is not likely to solve the problem unless this is combined with a good water change to reduce high nitrate levels.
• Algae eating fish such as tangs/surgeons, rabbitfish and dwarf angels will only eat certain types of algae… and only if they are hungry. “Overfed fish” are of no benefit in keeping algae growth under control.
• Out-of-control (and excess) algae may need to be removed by hand as much as possible to give the new algae eaters a chance to control it. Hermit crabs (small) and trochus shells are good eaters to add. .. so are rabbitfish.
   

The water pumps may not be not working or need servicing? This really means “not enough water flow’ Water pumps need regular servicing and generally the more hi-tech the pumps the more often servicing is needed. This is due to the high volume of water moved and the chances of calcification on/in the pump itself.

 

Associated problems with pump problems:

• Regular servicing essential. Tunze Turbelle streams pumps need to be back flushed every month or so, and taken apart and fresh water rinsed every couple of months (very quick & easy). Aqua Medic Ocean Runners need to be taken apart every few months to check the washers on the impellor shaft for wear, and also fresh water rinsed. Other pumps need to be checked at least every 6 months.
• Mimic nature with water flow. For good coral growth, we need to mimic the rough and tumble seen on the reef around most corals. This high water flow not only brings in particulate food for the corals But also removes unwanted by-products and residues such as oxygen in the day-time and carbon dioxide at night-time. A rule of thumb for most marine reef systems is a minimum of 20 times an hour water flow circulating. i.e. for a 500-litre tank, a minimum of 10,000 LPH water flow is needed in the tank. and it needs to be turbulent flow… Not laminar flow(round & round).