Buffering RO/DI?

[kevantheman35]

Anthony/others,
Would it be plausible to buffer your top of water with baking soda? I believe this would increase alk/ph as cheaply as possible.
I ask this as I am just now getting into dosing and realizing that my parameters are not what they should be, specifically alk and Ph.
Calcium=480-500ppm This never really fluctuates throughout the week as would be expected even though I have plenty of sps and clams water changes seem to be sufficient.
Alk=7dKH, I would like to get it around 10?
Ph=I have been continually getting readings of 7.6-7.8 which is scaring me, although I haven't seen any ill effects as of yet.

I have a suspicion that the low ph and alk of my top of water is gradually decreasing my tank parameters. I am in the process of trying to get my alk and ph where they should be through the use of b-ionic 2part. Then I am planning on adding kalk to the top off reservoir to maintain these values. I am hoping that the addition of kalk will make the addition of any other buffer to my top off water not needed. But can someone post a link to one of these said buffers?

 

[VegasRick]

It is possible to raise your alk with baking soda alone, I think you would be better off using a balanced buffer. Heres a link for recipes An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com

Your pH reads are low, which brings up more questions. Time of day you took reads, how are you testing it and have you verified the results.
More reading for you
Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com
Chemistry And The Aquarium: The Relationship Between Alkalinity And pH — Advanced Aquarist's Online Magazine

 

[Karen00]

All good, either way, my friend. I'm not one for taking the word of authorities or so-called authorities as gospel, regardless of their creds. Good information gathering is indeed about an informed consensus. And yet, if we take a consensus on a topic like this, you'll find that most folks do not reconstitute their demineralized water. Which would be fine if they could justify it, but like so much of hobby habits...its founded on misinformaton or an outright lack, thereof.

At the end of the day, what matters is adequate and stable mineral levels in the aquarium. And the fundamentals of what we are talking about here is maintaining adequate if not strong pH and alkalinity for better rates of calcification, larger bioloads, or simply the burden (steadily increasing dissolved organic) of a maturing tank in time).

These realities, made worse still by not uncommon scenarios such as a lack of water changes (reflecting the impact of unabated production of organic/nitric acids fro bioactivity), use of calcium reactors (CO2/carbonic acids also chewing up alkalinity)...

Erhhhm, I could go on. But you get the picture. The nature of aquarium keeping (all...fresh salt and brackish of course) is an acidic slide. We have to maintain pH and alkalinity (so much more important for pH stability) for the system we choose to set up.

Compound this by the reality that a lot of buffers are made, well...cheaply. Relying principally on sodium bicarbonate which was fine as a staple for marine aquarium keeping in the 1970's (example) when the few organisms hardy enough to survive archaic import and holding systems would in fact live in an aquarium sadly maintained with baking soda as a buffer (read: pH levels chronically under 8.0 and ultimately never able to go higher than 8.3). Its no coincidence that buffer manufacturers back then conveniently misreported (ahem) and promoted/advertised (cough) that a healthy marine aquarium should be kept between 8.0 and 8.3. To offer a better buffer than relabeled baking soda would have cost more, made less (profit) and sold less to tiny market of consumers not ready to spend big bucks like we do today. Ironic historical aside: the pushers of cheap buffer would ultimately place the responsibility for buffering on dolomite substrates or calcite...ironic because they do not dissolve readily until the pH drops to around 7.6. LOL (at which point you have a bigger problem than quantifying which was the better buffer, your cheap alkalinity booster or the crappy substrate you just bought.) [Note: aragonite will dissolve at a pH over 8.0...well over actually. Read: a better buffer support if you choose to rely on substrate for part of the duty]

So, we (hobbyists) shop and debate and argue online about sea salts and which has the higher pH and which has better Ca or Alk on mixing...without talking about the source water we are using to mix it up? Erhhhhm...?!? And salt some brands of which, albeit tried and true - all respect indeed - have not fundamentally changed their recipe in a gazillion years. Meaning...they formulated these salts at a time when almost nobody used purified water.

At the end of the day, it really doesn't matter how we buffer the water and insure better pH and alkalinity, so long as it gets done safely and hopefully consistently over time. And yes, there are sea salts that are formulated for use with RO or otherwise demineralized water.

But a majority of aquarists struggle with pH problems; very few consistently have a ph that doesn't drop below 8.3 at night let alone above it by day! And if you add raw, demineralized (RO/DI) evap water to your souring reef gallon by gallon day after day...how to you reckon that amelioration of water with 300+ ppm mixing with water with near zero ppm of hardness? For example...10 gallon (actual volume) of sump water at 10dKH gets 1.5 gall of evap top offf water each day with a pH under 7 and a dKH near nil, what do we expect the readings to be after the mix? Lessoned, indeed by the total volume of the system (maybe a 90 gall display this example). But day after day raw, sour, "pure" RO?DI water giong in and adding to the overall pressure on the system to keep pH and Alk up.

The simple fact is that demineralized water (RO/DI) is extremely unstable at any pH it comes to you (even sometimes even it is over 7). By aerating it (driving off CO2/carbonic acid) you will raise the temporary pH. And by buffering it slightly, you ease the burden and hedge your bets on the inevitable processes in aquaria ongoing after your water exchange that will bring down pH and alkalinity. There is no disadvantage to remineralizing your ro/Di water before it is used for evap top off or salting.

That is, I think...my short answer

FWIW, I do still use the old fashioned "tri-buffer recipe" (bicarb, carb and a borate) for dirty or bulk work...but I prefer to use well engineered products from thoughtful companies like Brightwell Aquatics and Seachem for this purpose.

This thread has been a very interesting read! I hope it's OK to resurrect it.

I'm a noob and am in the research phase of my journey into reef keeping. Just when I think I have my head wrapped around what's needed to keep a successful reef with stable water parameters I read a thread like this that challenges what I thought I knew. When it comes to water top offs due to evaporation most of the posts I have read mention adding pure RODI water however reading your reply about remineralizing RODI water makes sense as it pertains to maintaining stability.

You mention some brands that will accomplish this like Seachem but when I google buffering and remineralizing there seem to be a few Seachem products which leaves me totally confused as to what I should get. I already use Seachem for my FW tanks so would like to stick with that brand. Would it be their "Replenish" product or their "Alkaline Buffer" or "Marine Buffer" to accomplish remineralization?

I have also read a lot of people adding Kalkwasser to their top off water? Can this be used as a remineralized or is this used for other purposes?

When it comes to water changes and mixing new saltwater should the RODI water be remineralized first before mixing up new saltwater or do the salt mixtures take care of this? (I'm assuming the latter but wanted to confirm).

 

[Randy Holmes-Farley]

This thread has been a very interesting read! I hope it's OK to resurrect it.

I'm a noob and am in the research phase of my journey into reef keeping. Just when I think I have my head wrapped around what's needed to keep a successful reef with stable water parameters I read a thread like this that challenges what I thought I knew. When it comes to water top offs due to evaporation most of the posts I have read mention adding pure RODI water however reading your reply about remineralizing RODI water makes sense as it pertains to maintaining stability.

You mention some brands that will accomplish this like Seachem but when I google buffering and remineralizing there seem to be a few Seachem products which leaves me totally confused as to what I should get. I already use Seachem for my FW tanks so would like to stick with that brand. Would it be their "Replenish" product or their "Alkaline Buffer" or "Marine Buffer" to accomplish remineralization?

I have also read a lot of people adding Kalkwasser to their top off water? Can this be used as a remineralized or is this used for other purposes?

When it comes to water changes and mixing new saltwater should the RODI water be remineralized first before mixing up new saltwater or do the salt mixtures take care of this? (I'm assuming the latter but wanted to confirm).

I would suggest ignoring this thread. You resurrected a thread best left dead. lol

It predates my time as the expert chemist moderator of this forum and has plenty of misinformation in it. Do not remineralize RO/DI water for a reef tank. That is intended for making water for a fresh water (not seawater) tank, and not evaporation top off.

There is NO REASON to alter RO/DI water for top off unless you chose that as a way of dosing alkalinity (or calcium). Such methods are fine (I dosed kalkwasser for 20 years that way), but it is not needed.

RO/DI IS NOT EVER a cause of low pH. It would likely surprise the folks early in this thread, but adding totally pure RO/DI water at pH 7.0 to reef tank water at pH 8.1 will actually raise the pH of that tank water.

Sodium bicarbonate is a good way to raise alkalinity if you do not also want a pH rise.

If you want a pH rise, using carbonate or stronger yet, hydroxide, will raise both alkalinity and pH.

This may be a better place to start:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

 

[Karen00]

I would suggest ignoring this thread. You resurrected a thread best left dead. lol

It predates my time as the expert chemist moderator of this forum and has plenty of misinformation in it. Do not remineralize RO/DI water for a reef tank. That is intended for making water for a fresh water (not seawater) tank, and not evaporation top off.

There is NO REASON to alter RO/DI water for top off unless you chose that as a way of dosing alkalinity (or calcium). Such methods are fine (I dosed kalkwasser for 20 years that way), but it is not needed.

RO/DI IS NOT EVER a cause of low pH. It would likely surprise the folks early in this thread, but adding totally pure RO/DI water at pH 7.0 to reef tank water at pH 8.1 will actually raise the pH of that tank water.

Sodium bicarbonate is a good way to raise alkalinity if you do not also want a pH rise.

If you want a pH rise, using carbonate or stronger yet, hydroxide, will raise both alkalinity and pH.

This may be a better place to start:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

Thank you for this!! In light of the info you provided I think it's probably good that I did resurrect it so others like me who happen to read it will see the latest info you just posted and won't go astray by remineralizing their RODI water. LOL

I'm glad my original understanding to use pure water still holds true and that's one less bottle of stuff I have to buy. Haha! Thanks again for the speedy reply!!

 

[Randy Holmes-Farley]

Thank you for this!! In light of the info you provided I think it's probably good that I did resurrect it so others like me who happen to read it will see the latest info you just posted and won't go astray by remineralizing their RODI water. LOL

I'm glad my original understanding to use pure water still holds true and that's one less bottle of stuff I have to buy. Haha! Thanks again for the speedy reply!!

You're welcome.

Happy Reefing.