What should the specific gravity of salt be in a freshwater tank?

Question

I made a boo-boo a few months ago where I added too much salt to my 29 gal tank. So I have been doing water changes without adding salt, to rid the tank of the excess. Now I am afraid there is very little salt in the tank. So I bought a hydrometer, and for the life of me I can't find one website that has any info other than saltwater. This is not brackish, just fresh. My fish seem happy as can be after I almost killed the poor babies.

It just occurred to me from Biology class you man need to know the temp of my tank since well, specific gravity is relative to temp, expanding water and all. The temp at lowest, in morning, is 75 degrees. The highest temp, at end of day, 80.

Answer 1

For general freshwater fish keeping the level of salt is very low and may not even read on a typical hydrometer accurately. Adding a tablespoon per 10 gallons will give you 0.1% salt solution which is the minimum to see any measurable benefit in freshwater. For treatment of some fungus and parasite infestations, an amount of 0.5% is beneficial, while for treating other infestations and some bacterial infections a level of 1% is normal (1 tablespoon per gallon). The vast majority of freshwater fishes can easily tolerate a 1% solution with no problems at all and in fact most can easily handle double that, so odds are you didn't add enough salt to be of any significant problem.

You are correct that temperature and pressure affects salinity, but it's usually not factored in for aquarium keeping for several reasons. Mostly because the testing equipment isn't that sensitive and the differences made by temperature and pressure are still well within the fishes tolerances.

MM

Answer 2

My first question is - what size tank is this? The smaller the tank, the harder it is to keep things stable. I can only hope you haven't tried this in anything less then 25 gallons - preferably over 50 - small tanks are very difficult. Now, always, always top the evaporated water with the purest water you can - distilled water works perfectly. When water evaporates, salt, minerals, nutrients are all left behind and build up. By adding pure water to top it of you are ensuring everything remains stable and nothing builds up. As far as fish go - if you want a reef tank, don't worry about fish. Concentrate on the reef. Fish are messy with a higher bio-load, and you can always add them later on. Remember that a reef tank is not assembled - it's not built. It's grown over time. You start off with just live rock and sand. At this point you should not add any living creatures until you've proven to yourself that you can keep the tank stable in both salinity and temperature and are sure the tank is cycled and the live rock cured. Once you feel you've figured that part out you should start off with lower waste creatures then fish - what is usually referred to as the 'cleaning crew' - snails, shrimp, certain reef safe crabs - and then take your time and see how you do with these guys in the tank. One step at a time. Algae is a normal part of fish keeping, and especially common with reef tanks in newer setups. Don't worry too much about it - unless you have corals it can choke, they won't harm anything at this point. Just concentrate on your tanks parameters and instabilities for now. Keeping the lights off will seriously inhibit algae growth (and the growth of most other things in the reef system). You can still keep a reef tank even though you medicated - you just need to remove all traces of the medication from the tank and may want to add new live rock to the tank too. For now you shouldn't worry - worrying doesn't solve anything. Instead, learn and move on. *****(THE DIRECT ANSWER TO YOUR QUESTION) - If you still have livestock in the tank, do daily water changes with distilled water until your specific gravity is at 1.024. If all of your livestock has died and nothing is left, then you can safely start over and completely change the water and begin again using properly treated and dosed water. Then don't add any live stock to the tank, just practice keeping the tank stable and after this start off slow with the small invertebrates. If you can't keep things stable because your schedule doesn't allow it or the tank is too small, you had best reconsider a larger tank, or keeping a marine setup at all. Good luck.

Answer 3

you dont use a hydrometer for freshwater fish, nor do calculate the specific gravity or KH.


For freshwater it doesnt require alot of aquarium salt, but it isnt bad if you add alot.

Your not going to turn the tank into saltwater as the salt is really different. Saltwater mix is different from aquarium salt.

Answer 4

myself i put i teaspoon of salt to every 10 gallons of water... adding salt is a good idea it helps the fish to fight off diseases better...i have been doing this with my tank for well over 4 yrs and havent had a problem... so if it was my tank i would add 2 and a half teaspoons to the 29 gallon tank