My Oscars are coming down with something. The one had a shiny white
patch(when viewed at the right angle under lights almost a marbled effect)
and some white tufts protruding. Not sure if they were parasites - was
definately not fungus. I did some reading, particularly about hole in the
head although I can;t be sure that is what they have. Anyway I did an
immediate large water change and gravel vac and added salt. One site
recommended 1 tbsp per 5-10 gal.(how many ppm would that be roughly?!)

Since I do not know what a tbsp is (of course a table spoon but how much
is that) and do not have measuring cups I opted to weigh the salt and go
for a ppm or percentage solution and using the decimal system it makes the
maths really easy. But I just wanted to double check my maths here for my
own sake, and I am sure there are others who could benefit as well.

This is what I know

1mg (salt) / litre = 1 ppm
10000ppm = 1% salt solution

so if I have 350 litres to treat (trying to take into account the volume
taken up by gravel and rocks)and I want to add salt to get to 1000 ppm
or a 0.1% solution I do the following

1ppm * desired ppm * litres = salt to be added

1 (mg) * 1000 (ppm) * 350 (l) = 350000mg of salt = 350g or 0.35kg

since I only added 264g of salt I need a further 86g to get to 1000ppm

Is this correct?

And is 1000ppm (0.1%) a suitable concetration for treating the oscars for
a possible case of HITH along with more frequent water changes, gravel vac
and varied diet. Just that I do not want to be adding any meds or anythiny
without a proper diagnosis and having seen that even at the 754ppm
concetration level by the morning all the white things had disappeared and
the shiny white patches look less obvious.

The other fish are unaffected. I did do the only two tests I have kits for
and Ammonia was zero and ph between 7 - 7.4 (I have lost the color chart
but know the colour to be neutral to slightly alkaline) Temp runs at 26C
Filtered by a Eheim 22xx canister. I know I have slipped a littel in
gravel vacs but I do change at least 15% every two weeks.

I will be doing 10 % changes every 2 days (with gravel vac) and
adding enough salt to keep a 1000ppm level and investing in some varied
food - currently only feeding Nutrafin complete basic diet Floating
Pellets for medium and large cichlids.

Thanks

trev