How many TDS do you allow in your tank?

[rogersb]

We have lots of pic threads and plenty of lighting threads, but I do not see many water quality threads in terms of TDS on this site in general. So, how many TDS do you allow? I bought a used RO/DI set up a year ago and last night I finally hooked up my meter that I bought 6 months ago. From my tap is around 130 and after an hour of running I am getting 8 out of my unit. I have a mixed reef with plenty of zoas, shrooms, lots of LPS, and about 12 baseball size SPS colonies in a 60g tank. ( I don't run a skimmer)

If you were getting 8 out of your unit, would you run out and buy new membranes? I have no idea how long I have been getting this many, but I think my tank looks healthy and all my corals are thriving with no algae what so ever in the tank. I know the real issue is 'what are thsoe 8?' But if my tank is having no visible issues, is there cause for alarm?

 

[fsn77]

Do you know what the TDS is before it enters the DI stage?

To me, it sounds like your DI stage isn't functioning properly... If your RO membrane is removing about 95% of the 130 tap TDS, the TDS of the product water leaving the RO membrane should be around 7. It sounds like it's time to replace your DI resin.

Regardless, pre-filters only last so long and their purpose is to protect the RO membrane... If you haven't changed them and have been using the unit for a year or longer, it's about that time. The RO membrane will last several years, and the DI resin will last until it's exhausted. In my situation, I go through 2 - 3 sets of pre-filters in the amount of time it takes to exhaust the DI resin (that'll vary depending on tap water quality). In 4.5 years, I've not had to replace the RO membrane yet, but I know its days are numbered.

As far as what might be in that TDS of 8 you're seeing... It could be harmless or it could be something that doesn't result in anything negative until it accumulates in your tank over a long period of time. Considering how much money we all put into the livestock that goes into our tanks, I'm not inclined to take the risk of it being something potentially harmful. Replacement DI resin is cheap compared to recovering from a tank crash or even the loss of multiple coral colonies.

 

[MikeandNicole]

The goal is to always have zero. If it is 8 now who knows when it kicks up even higher as the membranes break down. I consider spending the money on keeping equipment up to date worth it if it keeps my corals alive (especially SPS).

 

[rogersb]

The goal is to always have zero. If it is 8 now who knows when it kicks up even higher as the membranes break down. I consider spending the money on keeping equipment up to date worth it if it keeps my corals alive (especially SPS).

I put this in the zoa forum to steer away from sps keepers. I have those colonies for now but have them sold. I'm waiting on the buyer to pick them up. I have been thinking the sps would prefer cleaner water, but being in the zoa forum do you guys let your water get a little dirtier?

 

[RokleM]

"Dirty" water typically is in reference to excess nutrients or extra feeding. RO/DI should be zero, zero, or.... zero

 

[MikeandNicole]

"Dirty" water typically is in reference to excess nutrients or extra feeding. RO/DI should be zero, zero, or.... zero

+1 even if you are getting rid of the SPS colonies.

 

[rogersb]

"Dirty" water typically is in reference to excess nutrients or extra feeding. RO/DI should be zero, zero, or.... zero

Thank you for the response. I have only been doing this a couple of years and if I have read this I must have not absorbed it because I honestly thought dirty would include TDS as well as excess nutrients. Well, that clears up a fewt hings I had rattling around in my head :spin3:

 

[dockery07]

Mine out of the RO/DI unit is Zero - but I can tell you from the tap mine is 1, I dont know what else is in the tap water but 1 is pretty good.

 

[Octoberfest]

My TDS meter reads 5 and I'm getting ready to order new filters (tonigh or tomorrow). Considering my TDS in the tap is 370 to 420 I'm not complaining. Living on the beach has its downsides I guess.

 

[DirectAquarium]

My TDS is usually 1-2 thats pretty good being I dont use the DI side.