Total Dissolved Salts in RO water

[bumblebee1976]

Hi all, I have had a most frustrating with a lfs regarding their RO water and readymix saltwater, so I just wondered if somebody could verify how important it is to measure the TDS? The first shop I went to for readmixed saltwater gave me water of too low a salinity and when questioned, blamed my hydrometer. When I took the water back with hydrometer in tow for them to check against their refractometer, they admitted the water was too low in salt. Apparently it was the first time it had ever happened! So then I get some more water mixed up and the salinity is ok but the nitrate level of the water was 50-100ppm using my Salifert test kit! This was denied again, their reading was 0!! When I asked about TDS, the answer gave was, 'We don't see the importance of this because nobody has been able to record exactly what is being read'. I have tried another shop and asked them to test their nitrate reading before I go in to collect and they haven't got a TDS meter. Should I buy my own and check it in the store before buying it? Thanks.

 

[carey]

A TDS meter reads the Total Dissolved Solids which should always read 0. Has nothing to do with salinity r nitrates.

I picked up a TDS meter on ebay for like $7.

if your LFS is selling water with nitrates and TDS then i would go elsewhere cause it's not much different than using tap water in my opinion.

 

[bumblebee1976]

Thank you. You confirmed what I thought. Quite. What's the point of paying for dirty water?!! What amazes me is that no other customer has a problem with it apparently. These are marine enthusiasts with huge tanks and expensive stock. Surely they would question it. My tank is only 60 litres, so starting off with this kind of water is way too dodgy for such a small environment. Yeah, I knew the total dissolved salts is different to the salinity and the nitrates, it's just that the store got those wrong aswell. I was told 0-5 is okay but my closest store has lost their TDS meter, so I guess I will just have to get my own. I thought the individual stores would get their water right before selling it!!! Apart from going 16 miles and leaving my carrier for the day while the saltwater is mixed up, I have nowhere else to try. I have completely lost faith in the retailer that got the salinity wrong when mixing up the first batch of RO, then tried to deny having any nitrates in the second batch. They also justified having a TDS reading of 40!!!!!!! Invest I will - going to try eBay. Thank you so much for your advice

 

[ccCapt]

Measuring the TDS of saltwater is sort of useless. There is no right or wrong reading. It would depend on many factors including calcium level, alk level, magnesuim level, trace element levels, etc. You only need to measure the TDS of RO water and that should be 0.
If you are buying saltwater that has a nitrate reading of 50-100 I would either look for a new place to buy it or get your own RO filter and mix your own.