I live no more than 10 miles from several popular bathing beaches in Cornwall, why would I want to spend £50 a month on manufactured marine salt, when I can get unlimited amounts of clean natural sea water (NSW) for free?
When I asked my local fish store “can I use natural seawater in my reef tank?”, the answer was a resounding “No”.
Against the warnings from the guys at the fish store, I set out and collected samples of natural seawater to run tests on its suitability for using in my marine fish tank. The water tested clean for Ammonia, Nitrite and Nitrate, with a specific gravity of 1.0235. After doing some extensive research on forums I soon discovered that loads of marine fish keepers are using seawater in their tanks with great success.
So far I have been using 100% natural seawater in the tank, I even had the opportunity to speak with one of the marine biologists at Blue Reef Aquarium in Newquay on the matter. He advised me that using NSW was fine as long as it was collected on an incoming tide, and not collected after heavy rainfall (to avoid run-off from farmland and sewage overflow). If it is good enough for the tanks at Blue Reef, then it’s good enough for me!
The Surfers Against Sewage website has a great interactive map which shows live alerts for sewage overflow events - click here to see map. – you can also click on some of the beach profiles which opens up an O/S map indicating sewage overflow pipes. (handy to know when I am planning to collect sea water). I also use their Sewage Alert Service, which notifies me of any reported sewage spills in UK coastal waters, it can be set to report for a huge number of beaches. This app is available for iPhone and Android – visit the Surfers Against Sewage download site here
I am currently collecting my natural sea water from the Towan headland at the northern end of Fistral Beach in Newquay. There is an old unused life boat ramp that runs straight into the water, I can park the car at the top and simply run down and fill 5 x 25 litre brewing buckets (£9.99 each from The Range). I don’t filter or treat the water, I just bring it up to temperature and tip it into the tank, simples! I do a 125 litre water change every two weeks, and the fish and corals all look very healthy.
If you are new to using NSW in your aquarium, or if you are considering it at the moment, feel free to contact me with any questions.
Keeping the tank clean (without a sump)
From my experience of keeping messy Triggerfish tanks years ago, I know that good filtration is a must to keep the water clean and the livestock healthy. Because I keep corals in my tank, the water quality needs to be pretty much immaculate. I test the water regularly and run a tight ship when it comes to maintenance and cleaning.
External Filtration - Because I have two cupboards in my Juwel 400 cabinet, I decided to put an external filter in each one, which maximises water volume and filtration capacity for the tank (I don’t run a sump on this tank). I have a Tetratec EX1200 in each cupboard stacked with Eheim Substrat Pro for biological filtration and ceramic rings for mechanical filtration. Many people argue that canister filters are “nitrate factories”, they certainly do a good job in quickly turning ammonia into nitrate. I then use other methods to export the nitrates produced in the canisters (explained below).
Protein Skimmer - To skim the water I have a Deltec MCE 600 hang on skimmer. Now that the skimmer is bedded in, it is extracting fish poop from the tank nicely – emptying the collection cup is smelly job though.
Controlling Nutrients – I run Rowaphos (phosphate removing media) in one of my external filters, I also run NP Bio-pellets in a fluidized reactor which outputs into my skimmer. This keeps the water in very good condition, and clean enough to keep both soft and hard corals.