How much would you consider a large shift in parameters?

[Ztous]

I'm new to salt water tanks and am trying to figure the basics out. I've had an empty tank setup (nothing but water rocks and sand) for two weeks now. My first week I mixed my water at 1.024 salinity and over the week it shifted to about 1.023. I assume this is from me taking small samples for testing and replacing it with top off water instead of mixed water. After my first water change it's now closer to 1.025 so I made a mistake and overshot a bit.

PH seemed to drop from 8.2 to something closer to 8 over the two weeks as well.

What I'm wondering is how much life inside the tank will tolerate once I begin adding it. Would a swing like this effect the tank or is that within standard deviation? Same goes for PH if I'm moving between 8.2 to 8.0 over two weeks is that going to be bad?

It's a 28g JBJ biocube. I've kept a lot of fresh water tanks but I've never kept delicate fish before, mostly North American stuff.

 

[shiftline]

This shifts are all Minor and nothing to worry about. Salinity you want to keep fairly stable wth an auto top but the one point will not hurt anything. pH will change on its own from day to night with the lights Also normal.

 

[Sk8r]

Ph isnt' as important to track as alkalinity. Get that test and ignore ph unless you have real weirdness that makes it worth watching. You want an alkalinity around 8.3, between 7.9 and 9. Letting it fall means fish fights and coral unhappiness. It is related to calcium (s/b at 420) and magnesium at 1300, not below 1200, if you're running corals. Fish-onlies worry about alk, but not generally cal or mg, though fish are very happy with the above readings. You also want phosphate so low as to be unfindable and nitrate to be around 2 for a reef, and under 20 for fish, even if they will survive higher readings. WHile you are cycling, things are not as optimum. But fish-load and inadequate amounts of live rock to tank/fish can cause high nitrate. So can having a filter sponge or anywhere waste gets trapped and held.

 

[Ron Reefman]

What you are seeing are very small changes and nothing to worry about. Just remember that in a 29g tank things can change fairly easily, so stay on top of it. And Sk8r's numbers are right on the money. Since you are just starting out, ammonia, nitrite and nitrate are most important to you as your tank cycles. Without sps or lps corals, your Ca, alk and Mg should be so stable that water changes will keep them in line. And some of the parameters have a solid floor like alk not going below 5 or 6dKH, but getting fairly high alk like 11 really isn't a killer. And you really want all your parameters to stay in a comfortable range and if they get out of line, don't drive them back to 'normal' too quickly. Big changes in some parameters is worse than having it out of the normal range in the first place.

I see salinity move from 1.023 to 1.027 over time and have never seen any issues in the tank. And it's a fairly easy parameter to keep stable as you are the one who has the affect on it, not the corals or fish.

When you have corals Ca, alk and Mg are three you want to watch. Especially alk. If it drops to 5dKH some corals will start to die. I keep mine in the 7-9dKH range, but I've seen alk at 12dKH (due to a dosing error) and had no issues. Ca is best above 400 if you have sps & lps corals. Higher isn't an issue as I've kept mine at 500+ for months at a time. The same goes for Mg with a floor of 1200 but some reefers even try to kill certain algae by raising the Mg to 1800ppm.

I very rarely even check ammonia, nitrate or phosphate any more as my system is very mature and stable and I have a solid filtration system given the size of my tanks. But your goal should be to keep them all as low as possible for the most part.

pH and nitrites should be fairly stable. Nitrites will only go up if you have an ammonia spike and will quickly turn to nitrates, so why even look for them once your tank has cycled. pH should range between 7.8 and 8.3 and movement up and down on a daily basis isn't uncommon. I haven't tested for pH in a couple of years.

You are smart to stay on top of these parameters until your tank matures in about 6 to 12 months. And in that same time frame you'll get comfortable with seeing the kind of fluctuations your parameters will take and how your tank responds. Just take your time. Oh, an asking questions is always a good idea!