Salting My System

Around 7pm, I found my Pleco sucking on a motionless tilapia fingerling. I then took it out of the water to examine it. It didn't moved for a while and I thought it was already dead until it started gasping about a minute later. Its body looked fine except for its brownish gills. I ran a stream of water through its mouth for a minute... But then I rethought about it and decided to cull it instead as it looked hopeless and I don't want it to rot and contribute more ammonia into the system...

To help them cope with their stress, I salted the water to 3ppt. I calculated that my system is currently running on 256 litres of water which should mean that I need 0.768 kg of salt to obtain 3ppt of salt concentration.

On the left: Roughly 0.76 kg of aquarium salt.

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Here's how to obtain the required weight of the salt:

• 3 ppt means 3 parts per 1000 in weight.
• 1 litre of aquarium water weighs very close to 1 kg.
• That means you need 3 kg of salt for every 1000 litres of water.

Now you need to calculate the total volume of water in your system in litres:

Rectangular Tanks:

width(cm) * length(cm) * water depth(cm) = volume(ml)
volume(ml) / 1000 = volume(litre)

Cylindrical / Circular Tanks:

radius(cm) * radius(cm) * π * water depth(cm) = volume(ml)
volume(ml) / 1000 = volume(litre)

* π = 3.1415926

Then you can obtain the amount of the needed salt by using this formula:

Salt weight(kg) = ppt number / 1000 * volume(litre)

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When adding salt into your system, don't just throw those salt crystals directly into your fish tank. Fish are curious and love to swim around the thick briny water surrounding the salt crystals and have a "taste" --- I know my guppies do. If they indulge for too long, they'll get salt burns on their skin.

What I did was I diluted the salt in a pail of water from the system. Stir the water to speed up the dilution process otherwise it may take hours. Once all the salt had diluted, you can dump them into the fish tank. The salt water will gradually get mixed together with the rest as the pump circulates the water. This sudden change in salt saturation levels is important as it will shock and kill most parasites in the tank osmotically.

* Note: Snails hate salty water and plecos probably won't be enjoying above 3ppt of salt.