How long to store mixed SW? Red Sea Coral Pro

[eitallent]

What is the safe amount of time to store salt water after you mix it?

 

The reason I ask is that I found a large pH drop in my stored SW.

 

I mixed up a batch of RSCP in my 32 gallon Brute bin as the instructions specify with RODI. The alkalinity, calcium and pH were all at appropriate levels for the salinity I mixed . Even though I mixed it just as instructed I still get the thick white precipitate on the sides and bottom of the bin and on the power head, but the water itself is clear (after the precipitate settles). If I agitate the water again the precipitate clouds up the water.

 

I have been using it to do small water changes for my 12 g and 125 g tanks. After two and a half weeks I had 10 gallons of the mixed SW in the Brute so I measured the pH to see if there was any change and it had dropped from 8.1 to 7.6.

 

I am not sure what is causing the drop in pH. Today I did the full foundation measurements on the remaining stored water and found that all the levels have dropped.

 

Carefully measured with Red Sea Foundation test kit (vials and syringes cleaned), stop watch, a calibrated lab grade pH meter and calibrated hydrometer:

 

Temp 76.4^o F

Salinity 35 ppt (hydrometer & adjusted for temp.)

Ca 360ppm according to RSCP salt it should be 455 - 475 ppm

Alk. 10.9 dKH (3.9 Meq/L) should be 12.3 - 12.7 dKH

Mg 1320 ppm should be 1360 - 1420 ppm

pH 7.58 should be 8.2 - 8.4

 

Today I mixed a new batch of RSCP salt in four gallons. Let the water sit for two hours and took measurements:

 

Temp 77.2^o F

Salinity 35 ppt (hydrometer & adjusted for temp.)

Ca 440 ppm

Alk. 14.30 dKH

Mg 1400

pH 8.0

[jcusmarine]

Forgive me for not posting a link to the info, but I recall RSCP advertises mixing without a Powerhead and recommends a certain temp and the mixing 30mins-2hrs prior to adding to aquarium.

 

I am very happy with RSCP. I religiously mix it 30mins prior to water change and do not store it.

 

I would stick with RSCP and not store SW, just store your fresh water and have it on the ready.

 

(EDIT)

 

Ok. Found the info for you as follows:

 

1. Use RO water that is at ambient in the UK a temperature of approximately 20OC/68OF is optimum .

2. Accurately weight the salt and measure the volume of water according to the salinity you wish to achieve.

3. Pour the salt gradually into the water. Do not pour water onto the salt.

4. Mix vigorously (without aeration) for approximately 0.5 - 2 hours, until all of the salt is dissolved and pH has stabilized to 8.2 8.4 - DO NOT mix for more than 4 hours.

5. When mixed, raise the temperature and add to the aquarium. (Not absolutely necessary for a small water change)

[eitallent]

Hi, jcusmarine.

 

Thanks for the reply. Thanks for the info too. I spoke to the RSCP rep and they said I may use a power head but NOT airstones like some people are inclined to do. Also, I only allow the water to mix until the salt is completely dissolve and turn off the PH. However the precipitate still forms over time.

 

There is not much I can do about the temperature (other than running it through a chiller which I do not own). In spring, summer and fall the house temp is 74 to 78 (with AC in summer).

 

I have decided to do as you say. Store the RODI water and mix up a fresh batch as I need it. I feel this is a bit dangerous if you need to do and emergency large water change because it seems to be a consensus among hobbyists that you should always wait a couple of hours before adding newly mixed SW to the tank. Oh, well the risk is small of that ever occurring.

 

Thanks again for your suggestion.

[AZDesertRat]

In 35 years of saltwater fish and reef keeping I have never waited more than an hour or two to do a water change and never experienced any problems. I think the day or two is an old recommendation from when salt did not dissolve and stabilize as quickly as it does today and from when we were using tap water instead of RO/DI which required time for chlorine and ammonia detoxification.

 

I usually mix and use almost immediately as long as the temp, salinity and pH approximate the display.

[eitallent]

In 35 years of saltwater fish and reef keeping I have never waited more than an hour or two to do a water change and never experienced any problems. I think the day or two is an old recommendation from when salt did not dissolve and stabilize as quickly as it does today and from when we were using tap water instead of RO/DI which required time for chlorine and ammonia detoxification.

 

I usually mix and use almost immediately as long as the temp, salinity and pH approximate the display.

 

Thanks for the reply, AZDesertRat. I agree with you and your experience makes me feel better about using the water right away.

 

I stored the mixed water for convenience of having the water ready when I had the opportunity to do water changes. I will now mix small batches on the day I need it.

 

Thank you for your help.

[Tbone675]

On the other end of the spectrum I keep my mixed SW for up to one month. I do WCs every month and I like to have it on hand just in case. The day before a WC I turn on the ph and heater and proceed to do my 90% WC. Been doing it this way for years.

[eitallent]

On the other end of the spectrum I keep my mixed SW for up to one month. I do WCs every month and I like to have it on hand just in case. The day before a WC I turn on the ph and heater and proceed to do my 90% WC. Been doing it this way for years.

 

Hello, Tbone675.

 

Which brand of salt do you use? Do you test the water before doing the 90% WC? If you do what are the paramaters?

 

Thanks for sharing your experiences.

[Tbone675]

I run tropic marin pro reef. (although I just made a batch of ESV but have not tried it in the tank yet...july 1st is almost here tho) the only parameters I check prior to the WC is the salinity and temp. Anything in this range is good to go by me - salinity 1.025~1.026 and temp 76~78. I notice the ph of the new water ~7.8 is lower than my tank water ~8.2 so I try to do WC at night before I go to bed when the tank ph is at its lowest ~7.9-8.0.

 

I honestly dont test that much anymore. i test alk once every month (mid month) just to be sure my auto dosing is on track still. (i will check alk also if i make a large change like add/remove sps) that is the only parameter I check.

[venturalvn]

I'm sure more people will start to chime in on this, but the way I understand it is it's fine to store over time as long as the water is being oxygenated and recirculated, such as leaving the powerhead on during storage.

 

I always store 5 gallons for my 20 long. I leave the powerhead on 24/7 and turn the heater on when I leave to work in the morning on the Fridays when I do my water changes. By the time I get home it's at the matching temp and I turn the heater off until the next time I need to do a wc.

[Tbone675]

I'm sure more people will start to chime in on this, but the way I understand it is it's fine to store over time as long as the water is being oxygenated and recirculated, such as leaving the powerhead on during storage.

 

I always store 5 gallons for my 20 long. I leave the powerhead on 24/7 and turn the heater on when I leave to work in the morning on the Fridays when I do my water changes. By the time I get home it's at the matching temp and I turn the heater off until the next time I need to do a wc.

 

i store mine with heater off and ph off just to save energy. i do turn them on 24hrs before WC day. not saying my way is the correct way but is a viable option.

[eitallent]

I'm sure more people will start to chime in on this, but the way I understand it is it's fine to store over time as long as the water is being oxygenated and recirculated, such as leaving the powerhead on during storage.

 

I always store 5 gallons for my 20 long. I leave the powerhead on 24/7 and turn the heater on when I leave to work in the morning on the Fridays when I do my water changes. By the time I get home it's at the matching temp and I turn the heater off until the next time I need to do a wc.

 

Hi, venturalvn. Thank you for you input. If I were to leave the power head running 24/7 the RSCP will precipitate very quickly and cloud up the water. RSCP salt must be designed to be used the same day or two. In the Red Sea videos they specifically warn against leaving the PH on after the initial mixing for this salt.

 

I just wonder at the pH change.

[bwoodward0012]

Had similar problems a couple years ago with his salt an Red Sea rep told me pretty much what you see above: weigh and add salt to RO water, allow to mix ( but not aerate) for at least 1/2 hour or until water is clear, then you can bring the newly mixed water up to the proper temperature and aerate, test salinity and ph once desired temp is reached and if they are at acceptable levels its ready to go. It seems mixing the water at a warmer temperature contributes to that white precipitate which leads to reduced levels of desired elements and pH. Storing the water for periods longer than 4 hours under the wrong conditions can also cause elements to precipitate. I followed the reps instructions then and still do to his day and have had no such issues. I add my heater at 1/2 hour and do the water change as soon as temp is reached (about another 45 min for me using a 100 watt heater to bring the temp from ~ 68* to 78*).

[eitallent]

Had similar problems a couple years ago with his salt an Red Sea rep told me pretty much what you see above: weigh and add salt to RO water, allow to mix ( but not aerate) for at least 1/2 hour or until water is clear, then you can bring the newly mixed water up to the proper temperature and aerate, test salinity and ph once desired temp is reached and if they are at acceptable levels its ready to go. It seems mixing the water at a warmer temperature contributes to that white precipitate which leads to reduced levels of desired elements and pH. Storing the water for periods longer than 4 hours under the wrong conditions can also cause elements to precipitate. I followed the reps instructions then and still do to his day and have had no such issues. I add my heater at 1/2 hour and do the water change as soon as temp is reached (about another 45 min for me using a 100 watt heater to bring the temp from ~ 68* to 78*).

 

Thank you for sharing your process. What you say makes complete sense.

 

How do you keep your water temp at 68 F in summer? Do you use a chiller, or freeze some of the RODI water?

Right now my water is about 78 F at room temp.

 

I mixed a 10 gallon batch today in two 5 gallon buckets and got very little precipitation. I used the SW after an hour of letting it rest. So far so good in the tank (125 gallon tank; water change of ~10%).

[bwoodward0012]

We keep our house between 68 and 72 normally so my water is usually around that temp already. Of late, due to my wife being pregnant, the thermostat stays at 65, I feel like an Eskimo.

[aviator300]

I realize this is an old thread but I just had to reply to it.

 

I use RSCP salt and pre-mix up to 4 days in advance without any problems. I have read all the posts on the subject and there is one thing that makes no sense to me.

 

It is said not to pre-mix the salt and also not to keep it mixing for more than 1 or 2 hrs or it may precipitate and cause other problems while circulating in storage.

 

My question is. What is the difference between storing, circulating, and heating the saltwater, whether its undergoing these things in the mixing tank or the display tank ?????

 

 

 

 

 

[aviator300]

bump

[tierarzt]

Excellent question..following.

[ChouDawg]

I realize this is an old thread but I just had to reply to it.

 

I use RSCP salt and pre-mix up to 4 days in advance without any problems. I have read all the posts on the subject and there is one thing that makes no sense to me.

 

It is said not to pre-mix the salt and also not to keep it mixing for more than 1 or 2 hrs or it may precipitate and cause other problems while circulating in storage.

 

My question is. What is the difference between storing, circulating, and heating the saltwater, whether its undergoing these things in the mixing tank or the display tank ?????

 

I just switched over to RSCP from the regular RS salt and have done two 5 gallon water changes. Each time I pumped water out of my "room temperature" RO/DI storage container, plugged in a wave maker style pump aimed at the bottom of the bucket, weighed out my salt by weight and added it in slowly. I set a timer and within 5 minutes I had crystal clear water and zero precipitate. I tested the pH/salinity of the newly mixed water, finished draining 5 gallons from the display and filled it right back up. Corals look great and my water changes are much quicker now. I've always done the mix like crazy for hours/days and heat in the past mostly just from what I read or was told.

 

My best guess for the difference is due to dilution and consumption. Due to the high concentration of trace elements in RSCP it can't stay super saturated like that for long. The combined low pH in most sealed mixing/storage containers and the addition of heat from a pump/heater can cause the elements to quickly fall out of solution. In the tank environment there is now much more water volume for these elements to remain in solution even with the addition of heavy aeration, temperature rise, etc..add on the fact that your corals are constantly pulling these elements from the water column and you have your answer. Another useful analogy would be a tank that is constantly dosed to maintain high levels of trace elements, at some point without any consumption that tank will be over saturated and you'll begin seeing precipitates. Again I don't have a degree in chemistry but my limited knowledge led me to this conclusion.

[jblank44]

Im gonna tag along on this one I'd love to hear these answers!

[pisanoal]

 

I just switched over to RSCP from the regular RS salt and have done two 5 gallon water changes. Each time I pumped water out of my "room temperature" RO/DI storage container, plugged in a wave maker style pump aimed at the bottom of the bucket, weighed out my salt by weight and added it in slowly. I set a timer and within 5 minutes I had crystal clear water and zero precipitate. I tested the pH/salinity of the newly mixed water, finished draining 5 gallons from the display and filled it right back up. Corals look great and my water changes are much quicker now. I've always done the mix like crazy for hours/days and heat in the past mostly just from what I read or was told.

 

My best guess for the difference is due to dilution and consumption. Due to the high concentration of trace elements in RSCP it can't stay super saturated like that for long. The combined low pH in most sealed mixing/storage containers and the addition of heat from a pump/heater can cause the elements to quickly fall out of solution. In the tank environment there is now much more water volume for these elements to remain in solution even with the addition of heavy aeration, temperature rise, etc..add on the fact that your corals are constantly pulling these elements from the water column and you have your answer. Another useful analogy would be a tank that is constantly dosed to maintain high levels of trace elements, at some point without any consumption that tank will be over saturated and you'll begin seeing precipitates. Again I don't have a degree in chemistry but my limited knowledge led me to this conclusion.

Precursor: I am new to the hobby, and I'm not familiar with the brand of salt, just stumbled upon the discussion and being a chemical engineer thought I could weigh in with some thoughts on the precipitation issue.

 

I think most of your conclusion is on the right track. The fact that corals are constantly pulling compounds out of the water only matters in a water change scenario where your previous statement of adding a super-saturated solution to an unsaturated one would give a better chance for solutes to stay in solution because of reduced concentrations. However if this were a brand new tank or if you did a sizeable water change (90%) then I don't see what would keeping it from coming out and the rate at which corals would absorb compounds and elements would not be fast enough to prevent precipitation.

The fact that an increase in temperature causes the precipitation when mixing points to calcium carbonate or magnesium carbonate or something similar. Most ionic compounds increase solubility with temperature. Carbonates tend to precipitate out with an increase in temp and or pH (scale in water heaters from hard water). This also may suggest an imbalance in the calcium/carbonate/magnesium concentrations in the salt mix. This is based more of what I have read about dosing and being careful to have enough mg otherwise you will form a precipitant in your tank when you dose calcium.

 

The fact that mixing may form the precipant too points to super saturation. If you have ever experienced a beer that was in the freezer and when you take it out and open it or hit it, it freezes, it's a similar reaction. A super-saturated solution needs a disturbance to give it the energy to start forming crystals, or it needs a pattern (another crystal dropped in, or air bubbles), to form around.

 

Without having too much experience in reef keeping it sounds like they are trying to balance out the chemical compounds in the salt to make up for which ones are consumed in greater proportion to the others. This would lead to a balanced water column but an imbalance in your pre-mixed water. Again though, a sizeable water change or outpacing your corals with the additional components from water changes I would think could lead to precipitation in your tank.

[MrZ2u]

Is there a prize for bumping an almost 2yr old thread ?

In process of putting up a tiny little 3.7 gal system. I dont know what the actual water volume will be after displacement by things other than water but I am guessing probably something like three gallons. I plan to change one gallon a week (suggest more or less if you have explainable reasons, I am open to suggestions) I have two, five gallon jugs. One will be full of RO and part of the ATO system. The other will be for SW. I want to mix four gallons at a time and do a gallon a week. The jug has an airtight lid.

I know Red Sea has their method but nothing about it makes sense to me. If the jug is sealed nothing gets in or out. Basic laws of science apply. What is wrong with my plan of up to four weeks storage on mixed SW? What am I missing?

[aviator300]

Nothing at all. Your absolutely right. Hahah..This is weird, I posted on this thread almost 2 yrs ago and it's still making the rounds.

[uwharrie]

I use RSP and mix fresh each water change per their instructions. I assume they are saying a short hold time due to precipitation of the minerals. Its a pain but I like the stability I am getting with the mix so follow their directions. I would love to be able to mix water once a month but not sure about storing the SW

[aviator300]

Yep your absolutely correct. In fact god has to mix the ocean fresh every week or two or it will precipitate also.

 

Nonsense.