# Switching a tank from fresh to saltwater



## Sebastian (Dec 27, 2012)

I have set up many freshwater tanks and a few saltwater ones, but I have never converted a running freshwater tank to saltwater. My question is if I can convert a 10 gallon bare bottom sponge filter tank by simply switching out the water? Are the nitrifying bacterial colonies the same, or will they be replaced?

The reason I am asking is that I found that with my 18 freshwater tanks I am constantly rearing fry and therefore hatching artemia. I always wanted to try myself on dwarf seahorses, but was afraid of the feeding aspect of it. Well, now I have bbs every day, so i might as well give it a shot...


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## Nave (May 28, 2013)

From what I have read (never done it myself) fresh and salt water colonies are completely different. You will want to slowly make the tank brackish moving your way to a full marine tank. As you make this slow conversion the fresh water bacteria will die at the same time the salt water bacteria will begin to grow. As I said before I have not done this myself, but have looked into it. I don't know how long this process can take. Someone whom has made this change should be able to answer that.


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## coralbandit (Jul 29, 2012)

Totally different bacteria,so just switch it over and use a cocktail shrimp(source of ammonia) to fishless cycle.
On the seahorse note I haven't seen captive bred dwarfs,but if you can find cb,or tank raised they will eat frozen mysis shrimp(more nutitous than brine anyway).Tank size is good as seahorses don't need a lot of room and are pretty lazy hunters.I kept two (non dwarf) in a 29 for two years till bloat? got them.You won't want to use the sponge filter either as bubbles are a no no for seahorses and saltwater in general.The bubbles can cause gas issues for the horse.


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## Reefing Madness (Aug 12, 2011)

Remove all the FW stuff. Mix up a batch of SW throw it in the tank, SG of 1.022-1.025. For the Sea Horse set up you can use mechanical filters, as you don't want a bunch of flow in there. Throw the shrimp in a small net, and lay the net across the water surface, doing this will keep it from getting all over the place when it start decomposing. You will need good lighting, as your going to need sea grass and such for the SH to hold onto.


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## Sebastian (Dec 27, 2012)

Thanks for your responses. I will just mix up the saltwater and start a new cycle, we will see how fast if goes. For mixing the water, can I used cured tap water? I know this is a no-no for coral tanks, and I used RO water for mixing back when I had saltwater tanks; however, there will be no invertebrates in this tank.

I am a little surprised that you are suggesting that the sponge filter would be bad. I read elsewhere that they are preferred for the dwarf seahorses because of their diminutive size.

This tank actually does not have strong light. Many people who keep these fish suggest not to use any live plants/rocks/coral, because of the potential hazard of introducing hydroids to the tank. I hate fake plants, but for the sake of the horses I will bow to them and create a fake sea weed scape with coral sand.


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## Reefing Madness (Aug 12, 2011)

I dislike using fake crap in a SW tank, thats not why I got into it. I prefer the natural look.
As far as the filter goes, don't mis cleaning the thing. If you do, you will find out why I think its a bad idea, but would work because they have really slow flow.


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## Sebastian (Dec 27, 2012)

Why is cleaning a sponge filter a bad thing? I have 18 tanks running on one linear piston air pump with around 25 sponge filters, all freshwater though.


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## Reefing Madness (Aug 12, 2011)

You'll learn.


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## coralbandit (Jul 29, 2012)

Aquarium Fish: Seahorse Care: A Basic Guide To Starting Your First Herd — Advanced Aquarist | Aquarist Magazine and Blog
I would urge you not to introduce bubbles to the horses enviroment.


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## Goby (Mar 21, 2012)

My husband and I attempted dwarf seahorses in a nano in his office several months ago. We failed miserably. We may try again. I have a 35 gallon tall Hex in storage that I might give a Greater SH-whirl this winter. 

Seahorse.com - Seahorse, Sea Life, Marine Life, Aquafarm Sales, Feeds and Accessories - Aquarium Life

For sea horse filtration seahorse.com recommends 2lbs per gallon live rock, a power filter with good surface agitation and a very long water-intake tube with protective a sponge, a protein skimmer, a UV sterilizer, power heads, and a sump.

He also talks about the ins-and-outs of sponge filters and under-gravel filters. And while it doesn't mention this on that site, a concern about improperly used sponge filters is, by humans term, Subcutaneous Emphysema. And while I've not personally dealt with SE in sea horses, I've listened to discussions about it at reef club meetings and attended a lecture that brushed over it at a seminar I went to. I've dealt with SE extensively in human beings though, so I grasp the pathology and can see how a sponge filter may increase risk. Beyond that, from everything I've read and learned the hard way...the recommendations on this site are note-worthy. There is another site called seahorse.org you could check out too if you haven't already. I'd also encourage you to participate in a seahorse forum in addition to other general fish keeping forums. I've found that seahorse people are hard core and generally know their stuff. With that, in every forum there are always those individuals who claim success even though they break all the rules. Ignore their advice. They're bored and likely narcissistic.

We used live gorgonians for hitching posts and they worked great. It's a natural hitch for SH. I still have the gorgs. We also used a few of these and the seahorses seemed to like them too and I didn't think they took away from the natural look of the biotope we were attempting to create. I'm with RM...I prefer the natural look.

We had several unexplained deaths which prompted me to rehome the rest of our little herd. I'm still not certain why they didn't thrive...but I will admit that I've spent more time learning about SH needs after I failed, than before, and I should know better. Seahorses are truly their own science...and so very cool.

I wish you success!


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## Goby (Mar 21, 2012)

Sebastian said:


> Why is cleaning a sponge filter a bad thing? I have 18 tanks running on one linear piston air pump with around 25 sponge filters, all freshwater though.


As you've already learned, sponge filters are some of the easiest filters to maintain...rinse and squeeze. I think they're awesome. That being said, seahorse.com explains that sponges may not be the best filtration option for sea horses. It doesn't completely discourage their use however.

Beyond that, the concerns of using sponge filters with Sea Horses is more of a safety issue...not so much that they won't work. I was instructed to install hydro sponges in such a way that didn't allow the sea horses, especially the boys, to sit directly upon the stream of bubbles. Apparently sea horses like to do that and then they get air trapped in their pouches etc. Basically, keep it in the upper parts of the tank.


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## Sebastian (Dec 27, 2012)

Thanks for the link Tom, had not read that article yet.

Goby, thank you for the detailed advice. I have joined one of the seahorse forums. This is a topic that I am not familiar with, so I am approaching it very slowly. Sounds really like I should stay away from my sponge filters, too bad. Makes sense to put them higher up in the water column; I also have hydrosponge filters with the relatively long extension tubes.


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