Bacterial growth during transition from FW to SW

[rixmodi]

I have a couple of questions regarding bacterial growth during the transition from FW to SW. I have read that extreme caution has to be taken whenever changing SG so we don't kill bacterial colonies already established in the tank. I have also read that at some point (SG 1.005-1.008) FW bacteria simply die off and new colonies, capable of developing under higher SG's, begin to develop. Are these bacteria just a modified version on the previous ones or another type? The question is asked because I am in the process of cycling (fish-less cycling) a tank for a GSP and I'll soon be raising the SG (the process began at FW). I will get a bottle of Dr. Tim's for FW in a couple of days and was wondering if I should use it given the situation presented above.

[J-P]

there in an article in the library (top link under the learn tab) on how to make the transition

There is also a thread that discusses the sensitive zone between BW and SW where both colonies of bacteria exist for a time and then make that transition

[Pufferpunk]

What SG are they being kept at in the shop?

[Brandon8521]

You have to be carefull once you get up to 1.008-1.014. Take it extra slow around that SG, and if you start to sea a crash (which you really shouldnt but just in case) you can allways bump it up to 1.016 and throw in some bio-spira. Im really not convinced that it is a completely different set of bacteria. The 3 Major nitrofying bacteria thats in the FW safe-start is the same bacteria listed to be in the SW bio-spira. I think its more or less the bacteria have a harder time adjusting to the SG changes so you have to take extra slow with them. Live rock however has tons more on it then just bacteria so once you get to 1.020 definitaly get some of that. Just make sure its well cured....

Another thing to point out is that you dont have to slowley rais the SG. You can just cycle the tank at full SW and drip acclimate the new GSP to full SW in a matter of about 1.004 an hour.

[RTR]

Permanent (i.e., self-replicating indefinitely in semi-closed systems - which is what our tanks are) bacteria are different in FW and SW. The critical range is as stated above, but I am conservative and am very slow over just a bit wider range to avoid any issues with unoxidized metabolites.

Bcummings8521 is correct in that you certainly can drip acclimate much more rapidly than you can do the gradual FW to SW adjustment. I admit I have had no problems from using that technique, but I still am more likely to do the slower gradual process than using the drip technique.. If you are setting the tank at the long-term density from the get-go, no bacterial additive should be needed if cured live rock is used - It takes care of that issue quite nicely. on its own, Alternate biofiltration should not be required and is in fact is not the most desirable addition - you do not want detectable nitrate in SW if you can avoid it.

HTH

[rixmodi]

What SG are they being kept at in the shop?

I have no idea because the guy at the LFS doesn't know. He told me that they come with "a bit of salt". Anyway I plan to go there with a hydrometer as soon as I get everything in order (still waiting for some items bought on the internet) before bringing the puffer home.

Another question: when mixing salt & water, I'm still getting white sediment at the bottom. Is this a sign that there is something is wrong?? The water has been mixing for two days. Should I simply try to filter the white sediment??

[Brandon8521]

If he doesnt know then i would imagine its freshwater (the little bit of salt is probably aquarium salt which does nothing for SG.) The LFS sounds really sketchy if he doesnt understand what SG is.

If there is white residue still sitting at the bottom of the container then its not fully mixed yet. How are you mixxing it and what kind of salt mix are you useing? Make sure you keep a good flow directed at the bottom of the container and it should mix well.

[rixmodi]

If there is white residue still sitting at the bottom of the container then its not fully mixed yet. How are you mixxing it and what kind of salt mix are you useing? Make sure you keep a good flow directed at the bottom of the container and it should mix well.

I just put the water on the bucket and slowly began adding the salt (instant ocean). The bucket has an air pump and a filter (without media) to keep the water running.

[J-P]

2 questions:

1) is the bucket large enough to hold the amount of water / salt (saturation)
2) a paint mixer attached to a drill will mix it more throughly and more quickly.. it is simple gravity, have you considered this?

I do not have any SW tanks as of yet... just throwing ideas out there. I don't know if they are good or bad.

[rixmodi]

1) is the bucket large enough to hold the amount of water / salt (saturation)

The bucket makes about 3.5 gallons. I'm trying to make 2 gallons at around 1.021 (following the instructions of 1/2 cup salt per gallon, although the hydrometer reads a lower SG).


Paint mixer and a drill... sounds interesting...

[Pufferpunk]

Is the water heated? What are you using to mix the water? Be sure to check with a hydrometer.

[Brandon8521]

One way to do it is to fill it with hot water first, thats what i do sometimes, Then mix it as best you can then fill with cold water and wait an hour then mix it again. Before I got to full marine i would just mix it let it sit for an hour then mix it again and put it in the tank.

The bubbler isnt really doing anything and can make a mess. Try getting one of those cheap submersable powerheads so you can direct the flow toward the bottom of the container.

[RTR]

Clarification: Any salt solution will affect a hydrometer/refractometer. You can make up a table salt solution to SW density if you try, but it will not of course support marine life. Specific gravity reflects how much soluble material is in the solution, it does not identify the specific salts in solution.

[J-P]

thank-you, thank-you!! I have never said that openly because I do not own a SW tank as of yet, but always thought that was the case

[RTR]

It is really just simple physical chemistry - the quantity of dissolved (not suspended) materials can be measured by resistance/conductivity or change in the refefractivity or specific gravity in the home or lab. Those measures are however crude in that they in no way describe particular or specific nature of the nature of the ionized materials responsible for the changes in the readings. Our hobby instruments cannot analyze, only tell us the total dissolved materials, not the components making up the solution.

Apologies for the tech-speak, but that sort of misunderstanding is widespread in the hobby. It is not often harmful, but it does make some folks think that a certain specific gravity (or refractivity or resistance) means that the solution is "right" for a particular life form. That of course is not true. - it is "right" only if the correct raw material is used to make up the solution initially.

HTH