Brackish Substrate?

[Dan04COBRA]

8) Hey everybody...

I have a 55gal & a 29gal tank. My 55gal is my primary tank and my 29gal tank has been the 'hospital/quaratine' tank with a resident pleco.

Anyways, I keep a small amount of salt in my 29gal tank. So to the best of my knowledge (not much about Brackish so this is why I am asking), I see that Sand is recommended for a Brackish tank, is there any reason why??

Since I have a blue rock in the 29gal tank now, I plan on pushing one half of the gravel over to expose bare glass, then fill the exposed side with the sand, wait about a week and remove the blue rock and finish covering the bottom with sand. Is this the correct way to do it with an already established tank?

Also, what is an 'ideal' temperature for a brackish tank?

My intentions are to keep a specie of Puffer fish. I am still researching the matter about what type of Puffer would live happily in a 29gallon tank. I will eventually be moving the Pleco over to my 55 gallon, so no worries!

 

[nmonks]

Hello,

There's no real reason to add salt to a tank containing freshwater fish. Certainly, the none of plecs actually need brackish water, even though a few species sometimes live in such conditions.

As for sand: coral sand buffers the water (raises pH and hardness) which is very good for high salinity things like scats, monos, shark catfish, and so on. Silver sand doesn't affect water chemistry at all, but in a low salinity brackish water tank, makes an excellent choice for fish that like to dig, such as gobies, flatfish, and so on. So ultimately you choose whether you want to raise the pH and hardness or simply provided a substrate for digging.

When changing substrates, you may as well do the whole thing in one fell swoop. Remove the fish to a large bucket (ideally a 10-gallon with a lid) and then remove the substrate. You can leave the filter running all the time. Put the new substrate it. The water may go cloudy, but this does no harm. Clean filter wool in the filter fixes this very quickly anyway.

The ideal temperature depends on the fish. Scats and monos like it around 25 C, mollies and archers a little warmer, around 28 C, while subtropicals like peacock puffers and hogchoker soles are better at 18-20 C.

For a 29 gallon tank, I'd be looking at figure-8 puffers, perhaps kept as a group. Green spotted puffers/Ceylon puffers are a little large to be really at ease in this size aquarium, particularly if you want to keep more than one, or add tankmates. Figure-8s are smaller, more peaceful, and basically hardy. Because they need only a low salinity (SG 1.005) adding plants remains an option. There's an excellent pinned topic in this forum on the subject. As far as tankmates go, gobies seem to work well.

Cheers,

Neale

 

[Dan04COBRA]

Wow! I didn't quite expect such an informative post as yours.

I really appreciate that information.

Maybe I can pick your brain a little bit about substrate?

'Sand' is not available in any of my local pet stores. They offer marine sand, but I know nothing about it so I looked past it. Some members have mentioned going to Wal-mart/Home Depot for sandbox 'play sand'. Tonight I made a trip out and could only find "Kolor Scape" play sand & on the bag it specifically said "Not for aquariums".

There was a mention of silicates (I think) in water if it were used....

Is it just a marketing ploy for pet stores to make $$ of their product or what? Can I use it anyways?

 

[nmonks]

Few pet stores carry sand, although any stores catering for marine fishkeepers should have coral sand. But if you want silica sand (silver sand) then a garden centre is the place to go. They sell the stuff, and it's used for making up potting compost for certain houseplants. It's usually called silver sand, and comes in two grades, sharp and smooth. You want smooth. It's very cheap: a 25 kg (50 lb) bag here costs around £3 ($5).

Silicates -- silicon compounds -- are what make up glass, silicone sealant, and silica sand. Glass and silica sand are chemically inert on a human timescale. It would take tens of thousands (likely millions) of years for glass to dissolve in water, which is why we still have glass objects from Roman times. Some aquarists have suggested small amounts of silicate dissolve out of silica sand into aquarium water, and thereby promote the growth of diatoms (a kind of algae than needs silicon to grow). There's no science at all that supports this. Diatoms may be able to extract silica from glass (or silver sand) directly, but they're going to do that from the glass and especially the silicone sealant that make up the tank, so adding silica sand is neither here nor there. In short, the silica sand = algae problem is a myth. There's a good summary here.

Some people have also used something called swimming pool sand, which I believe is used in pool filters. I have no experience of this, so can't comment beyond mentioning it. You'll need to do your own research on this.

Cheers,

Neale