Problem Keeping Inverts Due to Salinity Changes?!

dbg · Apr 18, 2014

I've had bad experiences keeping peppermint and cleaner shrimp in the past because of how sensitive they are to salinity levels. In my new 90g (no livestock yet!), I really don't want to have the same problem! So, I've got a couple questions:

First off, when I do water top offs to my sump, I just use fresh RO/DI water (with no salt added). I have found that when I add salt to the top off water, it seems to increase the salinity of the display tank, even when I use top off that is mixed to an SG 1.022. Hence, I just use pure fresh water... when I do it this way, it seems that the SG in the display stays at 1.022, even though I'm adding fresh water and not saltwater. Does anyone else do this?

Also, for monthly water changes, I know I will have to premix salt into the RO/DI in order to maintain salinity, but again, in the past when I have done this, it seems to make the display SG go higher than 1.022 even when my fresh saltwater to be added is at 1.022. Any thoughts/suggestions from how others do this?

Thanks!

dbg · Apr 18, 2014

I don't know if it helps, but here is the sump as well, in case anyone is wondering where I'm adding top off RODI.

EllisJuan · Apr 18, 2014

Always use just RO/DI for top off. When evaporation occurs only water evaporates and the salt stays. If you want stable SG, get an automatic top off. It does wonders for SG stability and saves you from having to add water everyday. It is one of the single best pieces of equipment you will buy. Once you have one you will wonder what you were thinking ever running a tank without one. This is from a person whose tank was up for nearly 3 years before buying one. Best $65 I have spent in a long time.

Sully · Apr 18, 2014

I've always been told that top offs are only freshwater (RO/DI or Tap), whichever you use. Water evaporates not salt. You may lose a minor amount of salt through salt creep but not enough to cause a swing IMO. With that being said, I had a somewhat major crash in my 20 gallon tank a little over a year after set-up due to my mistake of playing the tap water game for too long. I lost a hammer, Torch, all my mushrooms, all my zoas and a clown fish. The only thing that survived were a GSP colony, pulsing zenia, a feather duster, a high fin red banded goby, his pistol shrimp and all my inverts. The inverts included numerous snails (margarita, astrea, nasarius) several hermit crabs, and a peppermint shrimp. I'm not the best at top-offs. I sometimes have to add almost a gallon. Reason I'm telling you this is that my salinity swing would be way more than yours if your goo about your top-offs based on our tank sizes. This leads me to think that it is something else that is killing you inverts, but I have no idea what.

Sully · Apr 18, 2014

I'll also add that I have a 10g QT tank that's had a coral banded shrimp in it for over a year. I know he's made it through some salinity swings bigger than you should be experiencing.

dbg · Apr 18, 2014

If you want stable SG, get an automatic top off.

Thanks a lot for the info! Do you have a top off that you would recommend? and do you just set it up in your sump and connect it to a reservoir of fresh RODI?

Also, Sully, do you think that you had the crash because you were using just tap water?

dbg · Apr 18, 2014

Oh, and for 20% water changes, that is where you would want to premix salt into the new RODI, right?

EllisJuan · Apr 18, 2014

dbg said:
Thanks a lot for the info! Do you have a top off that you would recommend? and do you just set it up in your sump and connect it to a reservoir of fresh RODI?

I just use this simple one from autotopoff.com: AutoTopoff.com I use a Toms Aqualifter pump with it and a 10gallon Brute trashcan with lid as a reservoir. All of it together was less than $100. I fill the Brute once a week and it is never empty. It would probably last 10 days if I ran it dry.

Sully · Apr 18, 2014

Yes, mix your salt prior to water change. A day in advance is better if you can.

TrialandError · Apr 18, 2014

Your salinity needs to be a bit higher than 1.022 I believe. 1.024-1.025 is more ideal. It could be your salt level was to low in the past for the shrimp possibly.

Naiad · Apr 18, 2014

Never had a real problem with inverts and the gradual salinity change from evaporation and top off. I would look to another cause for not being able to keep them long term. Did you ever dose copper in that tank or check iodine levels?

fishroomlady · Apr 18, 2014

yes, I'm thinking the salinity is not the issue with your inverts.

VicD81 · Apr 20, 2014

Like everyone said water evaporates and the salt stays behind raising your SG! You should keep your SG @ 1.024-1.026. Since yours is low I would let the water evap till it gets to 1.025 and do a water change. Make sure your new mixed saltwater has the same SG (Take out a little and add enough to top off the tank). As for an ATO I would use a Tunze Osmolator 3155! Its got that electronic eye so inverts cant mess with it like they would with float switches. Just use a nice big Reservoir filled with plain ol Freshwater (RO/DI) That will keep you Salinity pretty constant, but then you have to take into consideration your Skimmer which is taking out saltwater, but that is minimal (Unless you're wet skimming) .

dbg · Apr 20, 2014

Honestly, I havent tried to keep any shrimp in my tank yet... I wanted to consult everyone to make sure I had a good idea of what to do before I went and got shrimp in my new tank.

I just use this simple one from autotopoff.com

EllisJuan, did you just purchase one of the single (or double) switch controllers and a pump from them, or do you need to order additional things from them in order to have an operational ATO? It doesn't seem entirely clear to me as to what constitutes an entire ATO device on their website.

A few years back I had the problems, but I never dosed copper; maybe I just used to have the wrong SG. Either way, everything you are all saying makes sense! =)

EllisJuan · Apr 21, 2014

dbg said:
EllisJuan, did you just purchase one of the single (or double) switch controllers and a pump from them, or do you need to order additional things from them in order to have an operational ATO? It doesn't seem entirely clear to me as to what constitutes an entire ATO device on their website.

I purchased mine from a fellow reefer. It is the double switch controller. The double switch has a second switch above the primary switch that will turn off the pump in the unlikely even that your primary switch gets stuck. I use a Tom's Aqualifter pump to move the water from my reservoir to my sump. It uses standard airline tubing to move the water through. Everything is available on their site and will run you ~$75 all in.