Koi Forum • SALT-3000 Salinity Tester/Meter : Koi Talk
I have one of these and and they are excellent value for money. On the right there is a small x10 icon flashing when you are over 999 which means you need to multiply the figure by 10. So if you are reading say 500 and the x10 is flashing then your TDS is actually 5000 which is 0.5%. salt. 500 without the flashing x10. Means you hardly have any salt in the system. Ie 0.05% and I am assuming you want to take the salt level in the pond up to 0.3%. So to get to this you need to add salt to 300 with the x10 flashing.
3% is way too much salt for a pond and should only be used in a short term bath no longer than 10 mins Max.
For a salt bath you don’t really need it as 1/2 oz per gallon of salt will take you to 0.3% so for a strong 3% solution you need 5oz per gallon. Personally I would never use salt baths at this level as I tried it once and the fish looked in agony. I prefer to treat with salt over a long period of several days in a quarantine tank and never above 0.9% as this dehydrates the fish.
You can also use it to find out the gallonage, by using the method in the pinned post in the koi health section
https://www.koimag.co.uk/forum/determining-pond-volume-using-salt-t559559.html. This meter measures in parts per million whereas the post measures in parts per thousand. So divide your readings by 1000.