FW to Light Brack - Cycling?

I can't find concrete answers for these anywhere...

I have a 45 G FW tank, which I am about to tear down and turn into a light brack tank for two F8 Puffers (pretty lightly stocked, I know). The substrate and filter will be replaced, though both will be used to cycle the tank into brack conditions (SG of 1.005-1.008) if required, or if even possible.

1. Can FW bacteria survive these light brack conditions, or do the SW-specific bacteria need to colonize? (I know there is a difference, but I'm not sure where the cut-off line is.)

2. Is it faster or even possible to cycle brack by cycling FW first (as is my case), or should I just restart the cycling process from scratch?

3. Do FW test kits work in light brack/low salinity?

Any help making the conversion to SG of 1.005-1.008 from FW would be appreciated. I'm at a loss as to how I could cycle a brack tank, considering that my tank will be lightly stocked, and that I know of no cheap fish that can be used to cycle the tank.

I've heard that adding ammonia helps, but I read that the proper ammonia to use is very hard to get. Household ammonia is apparently not good for cycling, as it has other chemicals in it.

RTR said:

The proper way to cycle the tank is to find out whether or not your LFS keep their puffers in FW or BW, and have the tank cycled at that level. If you are going to replace the filter and/or the substrate, do that in advance, not after the fish are in.

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I'm buying two F8s from someone looking to get rid of his, but not at the LFS. They are currently kept in brack water, but the fellow doesn't know the SG.

I actually work at the LFS. I've only been there for a couple of weeks. Don't worry: I fully intend to keep brack puffers in brack water. ( I'll find out tomorrow if my F8 "special order" comes in...)

I also put seven mollies in the tank a few days ago, to feed the bacteria while I bump up the salinity. One died, but it was looking pretty feeble when I got it. I found two bumblebee gobies in one of the tanks at work yesterday. One was already dead, but I took the second one home today. It seems very content in my partly-brack tank, and already ate some frozen bloodworms ravenously.

I was surprised to find it in the tank - it must have been well-hidden since I started the job. As with the two ADFs I found at work, the goby was probably not being fed properly. I tend to take home the small fish and frogs that need more than just flake food...

1. The cut-off specicific gravity for SW bacteria is higher than that required for F-8s, so the odds are that the bacteria are still the FW species.

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Sweet. I think my tank might be cycled, then. The water was cloudy for two days, but has cleared up completely. I'm slowly bumping up the salinity by putting 10 or 20 teaspoons of marine salt per day into a pantyhose bag, and letting it dissolve in the filter.

I doubled the amount of salt today, after borrowing a hydrometer from work. The water is salty to the taste (I can't resist), but a hydrometer reading shows the SG at only 1.000. It'll be hard to see how much the SG is increasing if the hydrometer isn't giving me a good reading. Could be the SG is too low for the hydrometer?

I figure there's a bit of a rush to set up the tank, since the guy who currently has the F8s houses them in a 5 G tank. They apparently used to be in a bigger tank, but the guy sold it.

3. Some do, some don't. That depends on the chemistry of the particular tests and brand.

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It turns out that my current freshwater kit is fine for my brack set up. Too bad I have a saltwater test kit coming in the mail...

Not other brands which the LFS says do the same (IME they do not), but the Marineland product does work.

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So I've heard, and so I've been recommending. I have yet to find this product locally, unfortunately.


Here's my LFS rant, as an employee ("Livestock Manager", actually):

There are too many people looking for quick-fixes and easy answers when dealing with fish. There are even more people looking to combine too many fish into too small a tank with poor choices in tankmates. I tell you, there are very few customers who take their fish's health seriously, or who bother to do what is best for their fish.

Also, working at the LFS is basically a minimum-wage job with pitiful long-term opportunity. Turnover is high. Training is minimal, and is usually done on the fly, IME.

Don't be too hard on the LFS employees. Write a letter to the top-level management (especially for the larger chain pet stores). After all, the teenager selling you a fish or hamster may very well be the cashier covering the livestock department due to short staffing.

I just did some water tests:

Ammonia: 0.50
Nitrite: 0
Nitrate: 0

It looks like my tank is cycling from scratch. That's pretty much what I had anticipated, even though my filter was already cycled for freshwater. No problem; cycling from scratch would take just as long as bumping the SG by 0.002 weekly to 1.008, as far as I know.

SG: 1.006
pH: 8.2
KH: 5 (89 ppm)

So far, so good. I use "Red Sea" brand marine salt. I also used sand from a hardware store as a substrate. I'm thinking of adding a bit of crushed coral to the substrate.

Here's where it gets weird:

GH: 62 (1109.8 ppm)

My highest recorded GH in my freshwater tanks has been 8 (143.2 ppm). Any idea why the GH would be so incredibly high, or if this is horrendous news? How would I lower this? A water change seems futile, since I would have to add more salt anyway, and I'm pretty sure the salt is what made the water so hard in the first place.

Yeah, I'm really new to the brackish water scene...

RTR said:

BW GH/KH/pH/TDS are all much higher than FW.

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I know this, but my test kit lists BW at about 21 degrees. Is 62 degrees exceptionally high? What range should I be shooting for? I freaked a bit after 30 drops in the test, so by 62 drops, I was having heart palpitations...

Why is my KH relatively close to my FW set ups, incidentally? At least my pH is bang on.

The test kit doesn't actually mention the SG of brackish water. It just offers some rough guidelines to GH/KH for various general types of fish (FW Rift Lake cichlids are listed between 11 and 22 dGH, for example, as are brackish fish).

Bah, I don't even care anymore. I've spend the last week trying to learn how to do this brack tank properly, and I still can't get a straight answer (same goes with FW tanks, though that's been about a year of ongoing research). I'll wait another week or so and toss in some F8 puffs. I'll keep an eye on the ammonia and nitrites, of course, to make sure the tank has cycled first.

I had my FW tanks set up for months before ever testing any of the water parameters. Once I finally got some test kits, everything looked good except for the occasional elevated nitrite levels (usually under 20 ppm, never over 40 ppm). This has since been corrected.

Having seen how fish are transported to the LFS, it's a small wonder how any of them survive. Having a fish die within 30 days of purchase probably doesn't reflect the conditions of the home tank. The vast majority of my fish casualties that occurred after a month since purchase were due to very obvious reasons, including stupid mistakes and a learning curve.

I think my F8s will do just fine once my tank cycles. I'm done worrying about it, and I'll intuit my way through based on my overall good FW experiences.

Thanks for your help, RTR.