Salinity

[corper]

What is the critical point for too much salt in the tank, and what is the affect on the fish other then death when it gets too high?

[BMW Rider]

Natural seawater ranges from 34-37ppt (1.025-1.027 SG) and 35 (1.026 SG) is considered the average reading. Fish are generally tolerant of salinities much higher and much lower than this, though they may not thrive as well. Invertebrates however are not very tolerant of a wide range of SG. Ideally you should try to maintain your salinity at a constnat reading that is as close as possible to natural seawater. The biggest factor though is the stability of your SG. Sudden large changes in salinity are very stressfull to all inhabitants.

[corper]

When I top up the tank with fresh water, I've been adding 5 gallons over 45 min. The tank is 72 gallons with a 33 gallon sump. The salinity changes from 1.028 to 1.025. Is this too fast? Also, I didn't set the tank salinity that high, I just never got a chance to top off last weekend. My salinity is usually at 1.024. My reason for keeping it lower than 1.026 is so that if I don't get a chance to top of right away the salinity won't go through the roof! Thanks for the help.

[monza]

Does your tank evaporate 5gal a day? Or do you add top up water when it goes down 5gal? Adding smaller amount more often would help for sure no mater what the answers to my questions are. To solve it all you could look at an auto top system.

Not sure if your specific rate of change is to fast but for sure if you can level it out it would be way better.

Dave

[Delphinus]

Holy moley, 1.028 to 1.024 (1.025) over 45 minutes? So basically everything is going through the same acclimation (e.g., a 3 point difference) that they probably went through when they came home from the store .... except that this is happening everyday.

I'm sorry but it can't be good. You should look at a slow drip system, float valve or float switch for topup. That way your SG will never vary .. or at the least it will vary imperceptibly. A slow drip may not be 100% match the rate of evaporation but if it can help you to make only minor adjustments on a daily basis (i.e., add only 1/4 - 1/2 gallons instead of 5).

Whether organisms can withstand varying salinities like that is going to depend on (among other things) where they live naturally, i.e., river estuaries, tidal pools, etc. will experience SG changes over a daily period but deeper water will be (usually) very steady. What we keep in our tanks tends to be a hodge-podge of animals from all over, so it stands to reason that some will withstand it, and some will not.

1.028 is a little too high. A SW fish can't drink water if he gets thirsty, they have to osmoregulate. So saltier water makes them have to work harder to keep from dehydrating.

BTW, 5g is a LOT of of topup for a daily addition. I'm going to assume you have either a large system, or at least a system with a reason for accelerated evaporation (e.g., halides and/or fans). A setup like that surely has a sump. If that's the case ... drill it for a humidifier float valve ($10 at Home Depot/Rona/etc.), use a 5g bucket for the reservoir, and fill the bucket once per day. Thus YOUR routine doesn't really change, but your tank will have steady SG over a 24hour period ... this will have a profound difference on your tank and how well it looks (really). And what's even better is it costs you less than $20. If you really want to geek out then you can look at float switches and whatnot ... or if it sounds too complicated then at least consider the daily drip thing.

Anyhow there's my $.02 on the topic ... HTH and good luck.

[Willow]

dude.. float valve in your sump hooked to a gravty feed bucket of ro water. 25 bucks in parts and less than an hour to setup! problem solved

[Tarolisol]

Originally Posted by Willow

dude.. float valve in your sump hooked to a gravty feed bucket of ro water. 25 bucks in parts and less than an hour to setup! problem solved

Not even 25 a bucket free with salt a float valve from homedepot 6 bucks some 1/4" tubing 5 bucks and your done.

[Willow]

what is the hd float valve you speak of? do you happan to know the brand name on it? i was talking about the kent one, usally between 20-25 bucks. i would like to get a few more for diffrent stuff though, i will have to check hd.

[Delphinus]

Dude ... () Just your usual furnace humidifier float valve. Take a look though the furnace stuff aisle. Should be about $10-12, maybe even less, I've forgotten offhand.