My Mistake No. 3 – Evaporation!!



When I first started out I had so many worries and concerns. I was monitoring many parameters and was always thinking about something that could go wrong. Is my lighting OK? Is my skimmer working properly? etc.


While testing my parameters one in particular was a constant issue, my salinity level. It was all over the place and on a constant rise. Been new to the hobby the salt mix was something I was already worried about and clearly I was doing it wrong? right? may be I was reading the mixture amounts wrong?


My Mix was spot on!



It was at this moment I broke my first refractmeter in a temper tantrum…


Straight to the forums to find out what was wrong and within minutes other reefers mentioned something I was giving no consideration to at all. Water Evaporation!


It was at this moment I bough my second refractometer…



My Mistake No. 3 – Forgetting About Water Evaporation!


#Q – What is Evaporation?



#A – Evaporation is the process of a liquid turning into a gas. Basically some of the water in our aquarium over the course of each day will leave the water column in the form of a gas. We can see this by the water condensing on the top of our tank covers. That is the condensed water that has evaporated.



How is this relevant to the marine aquarium?


If you think about other articles and posts that we have published on we always mention the key word in reef keeping, ‘stability’. Successful reef keepers are successful because they keep their water parameters stable and constant. They avoid parameter swings that can keep corals and upset fish.


Well the salinity level in a reef tank is simply another parameter that needs to be kept stable as much as possible.


As water evaporates from a saltwater system, all the salt and other stuff dissolved in it gets left behind. The more water that evaporates, the more concentrated these dissolved solids become—thus the higher the salinity gets.

If you don’t really understand the process of evaporation and why if raises the salinity level, simply get in touch!



How to combat Evaporation!


Basically you add the same amount of freshwater to your water column that you are losing via evaporation. Its that simple.

If you are using a sump, measure the water line in your sump and keep a constant check on it. This will indicate just how much water you are losing to evaporation. If you don’t have a sump simple measure your display tanks water line.


Some sites will actually calculate the rate of evaporation within your tank for you. I don’t know what these sites are called but I’m sure a simple google search will help find them.

There are many ways you can add fresh RO water to your system;



# Manual top ups


This is where you add freshwater (RO water) to your system on a regular basis. I use to add a bottle of water per day to my system to keep up with the rate of evaporation. I simply poured this in per night. It isn’t the ideal way to do this as the salinity level fluctuates throughout the day but its better than nothing.



# Doser


I use a doser to add small amounts of water throughout the day and night. This is much more effective and keeps the salinity level in my aquarium more stable. I only use a doser as I had one I was not using but it works well and means I only need to top up my freshwater storage container.



# Auto Top-up


The Auto Top-up unit has a sensor that measures the evaporation rate in your sump/ tank. This automatically adds the freshwater to the tank as it is needed. This is one of the best ways to combat evaporation and is very reliable. Many reefers prefer and use this method as it keeps the salinity level very stable and again, all you have to do is to top up the freshwater reserve container/ tank you are using.



So please don’t make my mistake and forget about evaporation!

It can be very costly in both time and money.