Fish, Tanks and Ponds


Fish, Tanks and Ponds
A comprehensive guide to fish

Collecting sea water

Rock pool
Rock pool

Introduction

Can I use water directly from the sea for water changes?

If collected and prepared properly natural seawater (NSW) is a great alternative to synthetic salts that are available in stores. After all, what would be better then keeping the animals in the same water in which they were born and evolved to survive? Although at first it may seem that this would be ideal and far superior to use over synthetic salt mixes, there are some potential disadvantages and precautions that need to be addressed before the water can be used in a captive environment.

Advantages

  • Proper salinity

  • Proper amount of trace elements, calcium

  • Inexpensive if you don't live far from a quality source

Disadvantages

  • Potential pollution

  • Potential of introducing diseases

  • Live plankton that can pollute the tank as it dies

  • Preparation time consuming

Collecting NSW

Make sure that the place that you wish to collect the NSW is relatively free of pollutants and runoff from the coastline. It's best to collect the water during high tide when fresh seawater is brought in by the tides. If at all possible collect the water from off shore areas at least one kilometre from shore.

Preparing NSW

NSW is saturated with organics and plankton. Most of this life can?t survive the rigors of life in an aquarium with hazards like changing salinity, pH, calcium, temperature, power heads, filters, protein skimmers etc. If all the plankton were to die off in the tank it could quickly pollute the water and potentially cause an ammonia spike. To prevent this, it?s best that you prepare the water before adding it to your tank.

Method one:

  1. Pre-filter the water using the finest sieve you can get.

  2. Place water in a solid, unheated, food grade container that no light can get into for a few weeks.  This is to kill off as much plankton as possible.

  3. At the bottom of the container you should notice a layer of debris that comes from the organisms in the water dieing.  Filter water from holding containers, being careful not to disturb that bottom layer, into another container.

  4. Aerate the water for a couple hours and bring it back up to the proper temperature.

  5. Test the water for ammonia, nitrite, nitrates, pH, alkalinity, calcium, and salinity.

  6. Make any corrections necessary for the water to be used in your tank.

Method two:

  1. Pre-filter the water using the finest sieve you can get.

  2. Run water through a strong UV sterilizer a couple times.

  3. Let water sit in a dark container over night to allow debris to settle out.

  4. Filter the water off (Can run through UV sterilizer again just to be sure)

  5. Aerate the water for a couple hours and bring it back up to the proper temperature.

  6. Test the water for ammonia, nitrite, nitrates, pH, alkalinity, calcium, and salinity.

  7. Make any corrections necessary for the water to be used in your tank.

Once you have determined the water is ready for your tank, you can use it to complete your water changes the same way you would use a synthetic salt mix.

Additional Information:

No matter what type of saltwater you use, either natural or synthetic, you will still need a source of freshwater, preferably RO/DI, to use for topping off the tank. In a captive environment, it is always important to continuously check salinity (specific gravity), pH, calcium, ammonia, nitrites, nitrates, and alkalinity. These items will always be in fluctuation and may occasionally require intervention though the use of additives to maintain ideal levels. Regular water changes may not be able to keep up with the changing water parameters, especially in tanks with heavy calcium demands.

Glossary

 

References