Question About TDS

Hi Guys,

I just my TDS (MH COM-100) meter in the mail and have been testing things. It tests for EC and TDS. I have been using the TDS part for the KCL calibration. The RO water coming out is about 0.1 or 0.2 ppm. It isn't perfect but better than the tap water I was using which is 121 ppm. My questions is this. I tested the bucket that I use to mix the salt and the small trash can I use under my tank for top off water. The bucket read at 9 ppm (has been sitting in it for several days), and the trash can read at 21 ppm. I do have a pump, hose, and top off float with plastic holder in the trash can. Could these be causing the rise in TDS? Also, are these reasonable results or should I be looking into other storage containers. Can anyone recommend any for mixing and for my top off water. The space is limited and I can only fit about a 3 or 4 gallon trash can in it. Thanks!!!

Regards,
Ivy

 

Could be that your containers are leaching stuff into your water. Try storing the water in a glass jar for a few days and then test that. If your tds stays the same as it was coming out of the r.o. unit, I'd look into buying new storage containers. Look for food grade plastics when shopping for new containers.

 

Are the containers sealed? I would suspect dust if they aren't.... Also, if it's in the tank with an open top sump it could be salt transfer.... like salt creep that gets in the air and lands in the trashcan.

Also, plastic is porous, if the pump or trashcan was ever used for any saltwater mixture it could very easily absorb some of that and leech it out over time. If it's just salt that's no big deal.

Also, most soft plastics like those used to make buckets and rubbermaid containers contain silica and phosphorus, I would test the water from the trashcan for phos and silica. Also, never assume "food grade" means "reef safe" they're not at all synonymous. Humans can tolerate a LOT more copper and phosphorus than a reef tank can. "Food safe" containers just means they're cleaned better from the manufacturing side... but many of those cleaning agents, like TSP, contain phosphorus. Wash everything before you use it, no matter what. You might get away safe with a USP grade or hospital grade container that's been certified sterile.

Water, bleach and vinegar are the only "reef safe" cleaners I know of, and with them you should let anything they've been in contact with dry for at least 24 hours to make sure anything left behind has evaporated... more for bleach than vinegar. FWIW, RO/DI water is a powerful solvent, and will clean glass as well as windex usually.

 

Thanks for the replies guys. I bought a food grade 7 gallon water container to store water in the basement and also stored some in glass last night. I tested both at they are reading the same as the RO unit water. I don't have either container really covered so it could definitely be dust, leeching, or salt from the sump. For good measure, I tested for phosphates in the top off container and it was 0. I don't have a silicate test kit yet but will probably order one when I order an iodine kit. The containers are brand new and have never had saltwater in them

Does anyone know of a small 3-4 gallon open container supplier for under my sump? Thanks again!!!!!

Ivy