Phosphates or Silicates slipping past TDS meter?

[jostafew]

No, I've never done a chemiclean. Closest I've come has been a 12 day complete blackout in my war against the dynos....

Will do a little reading on Chemiclean. If/when I start with a fresh batch of filter elements that might make sense to blow up what's in there and replace with a big ass WC made up of new water

[reefwars]

Originally Posted by jostafew

No, I've never done a chemiclean. Closest I've come has been a 12 day complete blackout in my war against the dynos....

Will do a little reading on Chemiclean. If/when I start with a fresh batch of filter elements that might make sense to blow up what's in there and replace with a big ass WC made up of new water

That would be my plan as well several small things together done slowly and you can be clear of this in a couple of weeks.

[asylumdown]

Just an FYI, Abbotsford gets its drinking water from 3 sources. Most of it comes from Norrish Creek and Cannell Lake, but at peak demand times they supplement the drinking water coming out of your pipes with water from the Abbotsford-Sumas Aquifer. A good friend of mine is presently doing his PhD on plumes of agricultural contamination in the Abbotsford-Sumas aquifer, and Abbotsford-Mission Water Services has published documentation acknowledging the nitrate problem with water from those wells. It's severe enough that they are unable to use some of their wells for years at a time because the levels are way over the legal limit for human consumption, and WAAAAAAAAAAAY over the acceptable limit for a reef tank. Abbotsford also adds chloramines to all the water from all three sources before sending it out in to the pipes.

An RO membrane won't do much to remove chloramines, it's the carbon stage that does that I'm pretty sure. I also think it will exhaust the carbon quite a bit faster than if it was processing water that did not have chloramines (I'm not sure if Metro Vancouver uses them, which is where Langley gets its water). Depending on when you changed your RO stages and how much water they've made since you've lived in Abbotsford, your RO unit may have been letting both chloramines and trace amounts of agricultural run-off in to the tank for months.

If I were you I'd get an RO unit with an extra carbon stage (or a chloramine specific stage if such a thing exists) before the RO membrane and start doing large water changes. I'd also nuke the existing cyanobacteria with a product like chemiclean as Denny suggested. People will tell you that cyano is the result of you adding too many nutrients, but what people don't realize is that cyanobacteria fixes nitrogen and carbon directly from the atmosphere (in fact it's one the most important nitrogen fixing organisms in all of evolutionary history), so you could stop feeding your tank for a month and the the cyano will actually continue to eutrophy the system all on its own. It certainly capitalizes on excess nutrients when available, but once it's established it can add organic matter and nutrients to your system just from metabolizing chemicals available in the air (plus a tiny bit of phosphate).

I have a working hypothesis that you'll never be able to get ahead of a nutrient problem with cyano present, as the cyano produces it as much as capitalizes on it, but that's for another thread...

[jostafew]

Wow, thanks for the background, it's much appreciated! My current RODI system has a 10micron mechanical filter followed by a 5micron carbon block and a 1micron carbon. They were both changed a couple months back but in order to really squash this one I'll be starting with a fresh set top to bottom.

I'm going to pass your reply on to my wife; last year she read somewhere that Abbotsford has some of the best water in the lower mainland... I tried to tell her that compared to Langley where we were it is terrible. At one point last summer we could fill the tub and it would be noticeably colored, it's always tasted dirty, and my TDS meter indicates on average 10x the dissolved solids in the tap water. Despite all that she wouldn't let go of that article on water quality hahah.

[asylumdown]

Yah compared to Vancouver Metro, Abbotsford has some issues. I think you *can* have really good water, but it all depends on what mix and from what sources you're getting out of your tap at that particular moment. Obviously it's always safe for human consumption, but 'human safe' and 'reef safe' have different thresholds.

The 'legal limit' for nitrate contamination is 10ppm, but that's Nitrate reported as Nitrogen (a weird yet standard practice in water treatment and some areas of chemistry), which is actually closer to 44ppm nitrate reported as nitrate, which is how we talk about it in the hobby. The good news is that the average nitrate levels from the other two sources are both below 1ppm, and Abbotsford publishes a report indicating that they only get 5% of their water from the aquifer wells per year (none of which have nitrate levels acceptable for a tank), but that's an average for the whole system over a year. Moment to moment you never know what the mix is coming out of your taps.

Interestingly, the other element that routinely tests above the 'legal' limit coming out of the aquifer wells is manganese, which just so happens to be critical to oxygen evolution during photosynthesis. I haven't been able to find anything that showed elevated manganese encourages the growth of cyanobacteria (though I haven't looked all that hard), but people have been testing cyanobacterial mats as a zinc and manganese remediation technology because they're really good at sucking it up. Food for thought anyway.

Anyway I think you're on the right track, good luck!