Backyard Aquaponics
A place to discuss aquaponics

I was at 1.5 ppt. I'm now up to 2.0 ppt. Is .5 over a few days a safe raise for tilapia and goldies?

First why do you want to raise it
Here in aust salting for ich we dose to 3 ppt straight up to shock the parasite
In extreme cases a salt bath of 20 min at 10 ppt has been used

It's a RAS system. I've been advised to keep salt at 3ppt.
I don't use any salt in my AP system.

Forget about salt if you have strawberry's
In my big system I used to run 2.5ppt
But after a few weeks you will find the plants will use it up

When my new fish we having issues I went form no salt to 3ppt 23 ½ pounds on about an hour. After I did that all my fish lived and are still living. That was weeks ago and my tank is still at 3ppt.

As you know I am new so wait for someone with fish experience to answer.

Good to know markb...thanks.

Coach, if you are salting for nitrites, I do not think it matters much, from 0 to 3 ppt in one step should be OK, but slower may be less stressful. Regarding fish, parts of a part per thousand are negligible when spread over an hour, much less days. I've always wondered if there was an effect on the bacteria, though. Slow and steady might allow better adaptation in the biofilters.
As F&F noted, for parasites you want to shock them, so the faster you raise the level the better.

I can't think of a reason why you would want to add salt slowly.

ALWAYS do it FAST.

ADD SALT AS FAST AS YOU CAN

The reason is if you are adding salts because of nitrates you want the salt in their ASAP to stop the nitrite ions being absorbed.

If its a medical treatment then it won't work if you add it slowly. Micro organisms are not very good at osmoregulation where as fish are very good at it. You want the salt content in your fish tank to jump quickly so that the organisms causing the problem literally explode due to the change in salt content in the water compared to inside their cells.

This also means that you want to add the salt to the FT or maybe the sump or probably even better the sump and the FT to get the salt concentration to jump in the FT AFAP but then as the water flows out of the tank into the GBs the salt content their doesn't jump so quickly.

To look after your bacteria if you run a FnD system then it might be an idea to stop the cycle for a while and run it as constant flood for a while. Might be one of those things that might make a small difference but lots of people don't bother and don't notice any problems with their cycling after salting.

Thanks Stuart, for the added detail, and the clarification of what I thought, and have done, but did not want to push someone else to do without the input of someone with larger scale experience. My bigger AP is only ~300l total. Most of my experience is just in pet aquaria.

I poured 12kg of salt into my AP1 FT (4000l) the other day, all in one go. Salinity at the bottom would have rocketted high for a while before it evened out. When it comes to Ich, hit 'em early, and hit 'em hard!

I don't think you need anywhere near that much salt for protection against Nitrites though

Sorry guys that should read NITRITES not nitrates.

Thanks guys!