Livestock care: buying Guide

updated Apr 2021

Product Reviews and Buying Guide

Many aquarists worry that CO2 injection may hurt livestock. Carbon dioxide and oxygen levels are independent of each other, so running carbon dioxide in our planted tanks does not necessarily deprive livestock of oxygen. However, high CO2 levels can still asphyxiate livestock. Even though plants produce oxygen during light hours, most tanks spend more time in darkness than light, so oxygenation is still important even in planted tanks.

Surface Skimmer and Lily Pipe

Above: with good circulation created by sufficient filter strength, the use of a lily outflow pipe and surface skimmer for the intake, one can significantly increase CO2 injection without fear of hurting livestock.

Tools to inject CO2 safely

  • A simple way to improve circulation is through a LILY PIPE as the outflow vent. This device is elegant and helps circulate water from the surface to the bottom, an important aspect of improving gaseous exchange. This allows better CO2 distribution (we suggest an inline atomizer like the one below), better oxygenation and allows you to 'overload' CO2 safely.
  • Another simple but powerful water intake device is the KOLLER SURFACE SKIMMER. By taking in water from the surface, it helps improve gaseous exchange by circulating the more highly oxygenated water through the tank's circulatory system. It also removes surface oils and proteins that can severely inhibit gaseous exchange.

The 4 water parameters

TDS: Total Dissolved Solids

It measures all dissolved organic & inorganic substances in the water. What makes up the TDS value matters infinitely more important than the value itself. 100pm of Calcium in water is relatively harmless, 3ppm of copper will kill most aquatic life. Dosing fertilisers in a planted tank will naturally raise the TDS value; in their simple elemental forms most fertilisers are non-toxic to livestock unless over-dosed greatly. The exception are terrestrial root tabs that contains large amounts of ammonia (e.g. osmocote+) or copper.

GH: General Hardness

Despite its fancy name, GH just measures the amount of Ca/Mg ions in the water (and other divalent cations). Calcium is present in most tap water. However, magnesium is often over-looked. Most plants are tolerant over a wide range of GH unlike KH. It is important to have about 4dGH if you are keeping shrimp.

KH: Carbonate Hardness

​Carbonate hardness/alkalinity - measures water's buffering capacity; the higher the KH, the higher the pH in absence of other chemicals in the water, and the more resistant the water is to downward fluctuations when an acid is added. Pure water with 0 KH will have a pH of 7. KH affects fish/plant osmoregulation and this variable should be kept stable.

​When people say that some plants prefer softwater, it actually refers to low KH/low alkalinity water, not low GH water per se. Picky species can be kept fine if the KH was low, but GH high. GH and KH can be adjusted/influenced separately, though the common compound that affects both at the same time; limestone (CaCO3) is what most commonly causes hardwater (limestone causes an increase in both GH and KH at the same time). Raising the GH without raising the KH can be done using calcium/magnesium sulphate; CaSO4 and MgSO4. Raising KH without raising GH can be done using potassium carbonate K2CO3.


​pH measures how acidic or alkaline the water is. pH fluctuations from CO2 does not harm fish (even though high levels of CO2 can). This is because CO2 is not a salt, and it is the changes in salt concentrations in water that impact osmotic functions of livestock. pH fluctuations because of KH flux can kill livestock; this is not connected to the change in acidity, but change in salt concentrations that impact osmotic functions.

However, extreme values of pH (high or low) can affect livestock if the extreme values are out the livestock's tolerable range. For most tanks pH values do not fluctuate to a point of being harmful as long as the KH is kept stable.

If keeping fishes that are less tolerant to low pH; one can consider buffering the water to have higher KH levels (3 dKH). This will prevent pH levels from dropping too low due to CO2 injection. For most tanks, having 2-3dKH of alkalinity is more than adequate to prevent water from becoming acidic to a degree that it affects livestock.


For increasing KH levels without increasing GH, use POTASSIUM BICARBONATE or NILOCG KH BOOSTER. Increasing carbonate hardness/alkalinity increases the pH of the water. This is done more for livestock than plants as most plants grow better in soft water rather than hard water. (Exceptions being Pogostemon helferi, Valisneria species).


API QUICKSTART contains nitrifying bacteria which effectively kickstarts the ammonia cycling process in a tank. A well cycled tank is far more resilient to algae and we advise good tank cycling before adding plants. Using Quickstart reduces cycling time to less than a week even when using ammonia rich substrates such as ADA aquasoil. SEACHEM STABILITY works in the same way.
​Ammonia such as DR TIM'S AQUATICS AMMONIUM CHLORIDE is used to start fishless cycling - this is food for bacteria to consume. This product itself doesn't contain nitrifying bacteria, which is where API QUICKSTART/ SEACHEM STABILITY comes in.


  • SEACHEM PRIME and SEACHEM SAFEare good dechlorinators. API STRESS COAT is another that we use. Safe is a powdered, more economical version compared to Prime, but the powdered version is very concentrated and may be troublesome for measuring out for smaller tanks. Prime has chelators that bind heavy metals.

Best kits to test water parameters


  • SERA and SALIFERT AMMONIA TEST KITS are reliable. Another commonly available brand is the API AMMONIA TEST KIT. For all these kits, the results take awhile to appear, colour change is not immediate. A tank should always measure 0 on ammonia tests as long as there are no recent spikes in ammonia for example, due to heavy feeding. Any positive reading indicates that the bio-filter still have time to mature. It also serves as a proxy indication that organic waste in the tank is not being processed efficiently. This is one of the key triggers for algae.


  • Use the SERA GH TEST KIT to test for GH levels. This kit gives much clearer colors compared to API's kit. GH measures Calcium and magnesium levels (combined) in a tank. Most plants do not require large amounts of either and tap water generally contains enough calcium that it need not be dosed. 2 to 3 dGH are good levels for most tanks and usually indicates that the water is quite soft. Shrimp/snail keepers might want to bump it up more depending on the species they are keeping. In hard water, GH may test upwards of 20 dGH. Generally, but not always, tap water that is high in GH tends to have higher KH as well, and this makes it unsuitable for growing plants that require softwater.


  • Livestock waste is the main contribution to nitrate levels in a tank. Some tap water also contain nitrates. Plants constantly uptake nitrates if they are growing. Green dust/spot algae is more easily triggered with high NO3 levels (>10ppm). SEACHEM, SALIFERT and SERA NITRATE TEST KITS will work well enough for hobbyist purposes. 


  • The NUTRAFIN PHOSPHATE TEST KIT and SALIFERT PHOSPHATE TEST KITare quite accurate for phosphates testing. Phosphates are produced by livestock waste and come in some tap waters. Aquasoil absorbs phosphates from the water column and this may cause aquasoil tanks to constantly read zero on phosphate tests. Plants rooted in the soil can still uptake phosphates from there. Generally, if you are dosing phosphates regularly through liquid fertilizer, one should not worry about the impact of getting a zero phosphate reading. Anywhere from zero to 5ppm are considered normal readings.


  • ​The HONEFOREST TDS METER is useful for quick TDS readings. TDS readings do not tell you the content of the water, it merely tells you the total amount of dissolved solids present (even that it is an approximate reading). It is useful to check for relative changes in value - the absolute reading is less useful. For example, if your tap water tests consistently at 50ppm TDS, the day that you test it and the reading goes up to 100ppm you know that something has changed. The TDS test does not tell you what changed though. To that end, planted tanks can work in a very wide range. Tanks grow perfectly well from 10ppm TDS all the way upwards of 500ppm TDS. What makes up the TDS (which can only be discerned through other test kits) is infinitely more important than the absolute value itself.

the 2hr newsletter