Water Change Before Adding First Fish?

[fantaman]

Hi All!
 
I have a 10gal FOWLR. It has been running for the past 4 weeks now. Added 6 small CUC in week 2. Checked parameters twice and both times saw the following: 
Ammonia - 0ppm
Nitrites - 0ppm
Nitrate - 5-10ppm
 
I have never done a water change (except for the occasional top off with RO and premixed Saltwater from LFS)
 
Do I need to do a water change before I add my first fish? 

 

[phantomlink]

Your mixing saltwater and R/O water?  Is this a freshwater tank, saltwater, or brackish?  I dont know anything about saltwater tanks it just seems weird

 

[fantaman]

This is a saltwater tank. When the level of water drops an inch or two, I add some RO and some saltwater to maintain the Specific Gravity at 1.026.

 

[phantomlink]

Ah, well usually water changes after a cycle before adding fish is generally done to remove large amounts of NItrates from the water, however in large planted tanks and saltwater, Nitrate levels are pretty low, your Nitrate is lower then my tap water

 

[CezzaXV]

You'd probably get a better response down in the marine section.

I'm in the process of going marine, so I will attempt to comment.

When topping off, you should only use plain RO water, not saltwater. This is because while water evaporates, the salt doesn't, which causes the SG to go up. When you add more fresh RO water, it dilutes the salt which causes the SG to go down. 1.026 is acceptable, though a little high in my opinion. If your SG rises because of evaporation you're immediately into the danger zone. SG should be between 1.024 and 1.026, although some sources say you can go for less than that if you're FOWLR, as you are.

Might be worth checking the SG of the premixed stuff you're buying in. I'd be surprised if your LFS is adding more salt than they strictly need to.

I would personally do a water change, just a normal one (no more than 20%) before adding fish. While you're okay for nitrates, much more is going to start causing problems (marine fish are much more sensitive to nitrates than tropicals) and it's a good idea to get into a regular habit now. I can't be sure, but I would imagine that with marine it's much the same as tropical - inverts don't really create enough waste to be noticeable.

Just out of interest, are you using a protein skimmer?

In my, admittedly, fairly limited opinion based on the marine knowledge I currently hold, your tank is fine, but it's on the upper end of fine. I'd wait for someone to agree with me though before taking my advice.

 

[fantaman]

Thanks All! 
 
1.026 was a typo. I maintain my tank at 1.024. I noticed that there's a lot of salt deposit on the heater, filter and glass top (which I clean out). So when I check the SG after losing a couple of inches off the top, I dont see too much of an increase in it. As a result I balance it out by adding a little Saltwater along with RO. End result is 1.024.
 
I am not using a protein skimmer as my limited reading yielded that it is not typically required for a tank of my size (10gal) 

 

[CezzaXV]

1.024 is fine, and gives you some leeway for when evaporation occurs and the SG rises. I was surprised that premixed saltwater would have more salt than it needed.

You're probably right about the protein skimmer (I've not done a massive amount of research on the topic of skimming yet). Many tanks can get away without being skimmed, although a skimmer will help keep nitrates down as it removes the stuff that rots down and creates nitrate. I've just done a bit more reading on the nitrate level issue and (according to About.com, at least) up to 40ppm is acceptable for a FOWLR tank, though to me that just feels wrong and I'd do a water change long before it got to that stage.

Marine fish are much more sensitive to changes in water parameters than tropicals. Tropicals are used to living in rivers and lakes where flow or rainfall can bring in new water with different parameters, but marines live in the massive body of water that is the sea, so they just haven't evolved to be able to handle big changes. I wouldn't change any more than 20% of the water at a time, which of course means that if you let your nitrate get bad, there's no way of quickly getting it down, meaning it's important that you get used to a regular water change routine. The goal is however often you change the water (and different sources will tell you different time frames), that your nitrate never gets even near a dangerous level, and that you're removing it quicker than it's building up.

10g is a very small tank to have marine fish in, so make sure you keep an eye on those parameters. Even a small amount of waste can cause a big rise in nitrate, and only a small amount of evaporation needs to occur for the SG to go up. The upside though is that with such a small amount of water, a water change can be done with a jug in a matter of minutes, especially if you're buying the saltwater instead of mixing it yourself.