How to sterilize sea water

[LuckyFish]

That´s a quick and easy thread, but I want to keep this separate, so it will be easy to find if needed.

If we don´t use artificial salt and RO water to make a sterile sea water, we have to sterilize the sea water we want to use for our phytoplankton and rotifer cultures.

Why? I think that should be clear. With growing algae in unsterilised sea water, we grow also some species of zooplankton. The chance to get green water is next to zero. Even for the rotifer culture, we have to sterilize the water, because any other zooplankton is unwanted in the rotifer culture, except brine shrimp (see note below). Rotifer cultures have to be rotifers only, because any other zooplankton will go into competition with food and habitat. Rotifer will grow with other zooplankton, but in low density. We want high density.

To sterilize 1 litre seawater, use 1 ml regular, unflavoured bleach.

Example: Add 20ml bleach into 20 litre seawater. Stir it, let it stand for a few(3 to 4) hours, stir it again, let it stand for another few (3 or 4) hours.

Now the water is sterile, but we have to get the bleach out. Strong aeration for a long time will work, but it takes time and we feel not so safe with it.
Better is the use of sodiumthiosulphate. It is used as a dechlorinator.




These diamonds are the breeders best friends!


How to make a stock solution?

250 g sodiumthiosulphate diluted in 1 litre water

or

25 g sodiumthiosulphate diluted in 100 ml water.

To neutralize 4 ml of bleach, we need 1 ml of the stock solution.
With 100 ml stock solution we can neutralize 400 litre sea water!

Example: We used 20 ml bleach to sterilize 20 litre sea water.
To neutralize 20 ml bleach, we need to add 5 ml stock solution of sodiumthiosulphate.
4ml bleach, use 1ml stock solution
20ml bleach, use 5ml stock solution

After adding the right amount stock solution, put a airline in the water to aerate the water. Let it bubble for another few hours. If you can´t smell the bleach any more, the water is ready to use.


Note: Why did I write, any other zooplankton is unwanted in the rotifer culture, except brine shrimp.

In every single rotifer culture you should keep also a few (5 to 10) brine shrimps, depending on the volume of your rotifer culture.

Why?

The brine shrimp will grow out in your rotifer culture. That will take roughly 2 weeks.

So you can see your bigger brine shrimps easily in your rotifer culture. If your brine shrimp disappears, you have to make a big water change.
Your rotifer culture is going to crash! Brine shrimp means, rotifers gone in the next few days. If you rotifer culture crashed, no need to panic.
Make sure to have always 5 litre phytoplankton for the worse case.
If your rotifer culture crashed, stop the aeration, let the water settle and syphon out the sediment. Put the sediment in your 5 litre emergency phytoplankton bottle.
Wait a few days until water turns clear. Now you got enough rotifer to start a new culture.
Rotifer knows before you, when the culture is going to crash. They will produce cysts instead of babies. Nature is good, hey? You will have plenty of cysts in the sediment of a crashed rotifer culture.

More about rotifer in a new thread.

[jean19]

i don't know anything about rotifer but instead of using bleach why not just boiling or micro waving the sea water ??? i'd prefer it than bleach and unbleaching stuff .

[LuckyFish]

Originally Posted by jean19

i don't know anything about rotifer but instead of using bleach why not just boiling or micro waving the sea water ??? i'd prefer it than bleach and unbleaching stuff .

Because my microwave is to small and I don´t have a big pot.

I am sure, one day everybody will experience that his algae culture got eaten up by rotifer. In that case you have to sterilize your container, airlines, taps, etc. as well.

Bleaching and neutralising is standard procedure in aqua culture. Easy and cheap to do.

[FransSny]

thanks luckyfish, never knew that. Just a quick question, wouldnt running it through UV also kill off everything thus rendering the water sterile ?

[Warr7207]

Do we have Rotifers in all our tanks ?

What do they look like, pod ??

[LuckyFish]

Originally Posted by FransSny

thanks luckyfish, never knew that. Just a quick question, wouldnt running it through UV also kill off everything thus rendering the water sterile ?

UV will work. I did it in the beginning without any problems.
But after a while, the tube from the UV becomes a thin layer on it and the UV is getting less and less sufficient.
I also thought, to much hassle with bleach and stuff. Now, since I use bleach, it is so much easier and safer. And when you think about it, you use just 1ml bleach to make 1 litre sterile.

[LuckyFish]

Originally Posted by Warr7207

Do we have Rotifers in all our tanks ?

What do they look like, pod ??

No, we don´t have rotifer in our tanks. I can´t imagine that. But we don´t want to have all the other critters in our cultures, like pods.



Rotifer we use in aquaculture, is called Brachionus plicatilis and they have an average size of 239 micron, which is roughly a quarter millimetre.

[jacquesb]

Many thanks for sharing this, LuckyFish. This is really interesting.

[Haddock]

I am thinking about using seawater for water change on my reef tank system that I I am planning.

It is rather large with a total water volume of 1500 US gallons (6000 liters) and the cost for using artificial sea water is therefore high.

One could always argue that the cost of salt for producing water is low compared to the total cost of the system but I feel that given the chance to use sea water I should do so.

I have access to very clean natural sea water at next to no cost close to where I live.

Does the method above apply to my use as well? Is there any way that I can make sure that the water is safe to use after a treatment like this. I mean, the loss of a rootifer culture is nothing compared to a stocked reef tank this large....

Also, what would be the storeage time for this sterilized water? Are there any way that I could continously treat the water that has been sterilized to make it storable?

Thanks everybody

[clinton stanford]

Originally Posted by Haddock

I am thinking about using seawater for water change on my reef tank system that I I am planning.

It is rather large with a total water volume of 1500 US gallons (6000 liters) and the cost for using artificial sea water is therefore high.

One could always argue that the cost of salt for producing water is low compared to the total cost of the system but I feel that given the chance to use sea water I should do so.

I have access to very clean natural sea water at next to no cost close to where I live.

Does the method above apply to my use as well? Is there any way that I can make sure that the water is safe to use after a treatment like this. I mean, the loss of a rootifer culture is nothing compared to a stocked reef tank this large....

Also, what would be the storeage time for this sterilized water? Are there any way that I could continously treat the water that has been sterilized to make it storable?

Thanks everybody

welcome to MASA! Haddock that is a huge system you going to be building why dont you start a thread in the new members section and tell us more about your plans.and we can all welcome you to this awesome forum

[LuckyFish]

Welcome to MASA, Haddock.
In your case, do it like I do. I always store NSW for a few weeks in 25l cannisters.
When I do a water change in my broodstock or growout system, I pour the cannister into a 65l bucket and pump it slowly(10litre/min.) through my UV sterilizer, before it goes into my systems. You must know, it is very safe, because you will use the UV only, when you pump it through and then into your system.
You must also know, I have to be very safe, because in my systems are swimming the only albino clowns worldwide. So these clowns got a very high value. The use of bleach and sodiumthiosulphate is too risky for me. As you mentioned, if a rotifer culture dies, that is not a big deal compare to livestock with a very high value.
So we both sitting in the same boat. By the way, the tank I had in Germany was 5.500 l and the systems total was 7.500 l.
Please open up a new thread about your project. Tanks like that a rather rare and we all can learn from your progress or you from us.
Enjoy your stay on MASA.

Marcel