Saltwater Mixing

dvybiral · Nov 5, 2019

Hello reefers, My question is who uses a pump for mixing and do you leave it on and circulating the water 24/7 until you need to use it, or do you just use it to mix and then shut it off and remove it or leave it in the tank. The reason is that I usually make up 40 gallons of new saltwater anywhere from 3 to 6 days until I will need to use it, with a pump running 24/7 for the weekly water change, and I am having Aluminum show up on the ICP test. I have had my RODI water tested and it is good. I have gone thru the my entire set up and there is no metal rusting in the tank or sump, and I do not use marine pure, if that is really true that it leaches aluminum. Could a pump be causing the aluminum in my water?

MTBake · Nov 5, 2019

I leave a pump running in my mixing container when ever there is saltwater in there. Not sure it's really needed once the salt is mixed though.

Jeto2004 · Nov 5, 2019

To question one:
Yes the mixed saltwater needs agitation to have it ready for your water change if you store it. However, my mix pump is controlled by my apex and runs for 5 min every 15min.

question two:
Does saltwater come into contact with unpainted aluminum inside your pump? Have you disassembled it to have a look?

AllSignsPointToFish · Nov 5, 2019

I actually just mix my salt into the water immediately before adding it to the tank as long as the temperatures match. I've been doing it that way for years. I don't leave mixed saltwater mixed overnight or for days (don't have the space or cooling to prevent the water from getting too hot as I have a large mixing pump).

Hallowhead · Nov 5, 2019

I leave my jebao dcp 2500 running 24 hours a day along with a heater until I use the water.

Just like your return pump it's okay to run constantly

lapin · Nov 5, 2019

I mix my water the same day I use it. If for some reason I can not use it I turn off the mixing pump for the night and restart mixing 2 hours before I use it. My barrel has about 10 gallons in the bottom I do not use. It gets mixed in the next week. I have no aluminum issues.

LAReefer4Life · Nov 5, 2019

I have the powerhead running 24/7 with heater and add it anywhere from 6 hours - 4 days after mixing.

BeejReef · Nov 5, 2019

The little I know comes from binging the BRS video series.
Based on it, I heat and mix my saltwater for 24-48 hours and then just let it sit without further mixing or heat.
The night before a water change, I turn the pump and heat back on, do WC, then off again.

Aluminum is a common complaint. Did find a metal hose clamp on my mix-bin pump (since removed). Can't say if that was the culprit or not bc have not done follow up ICP yet.

My personal theory is that aluminum often is part of lighting and mounting assemblies.. DT lights, fuge lights, etc. The outsides may be treated, but a lot of them have cooling fans that blow all the internal corrosion all over your sump or DT.

Ever looked inside a fuge light? It's not prettty

Bossman · Nov 5, 2019

This is something I wasn't aware of. Why does the salt need to be agitated once it's already mixed? I use Red Sea Coral Pro and once it's mixed I shut off the pump. Usually use it the same day, but I have left it for days with just the heater running before I use it.

Hallowhead · Nov 5, 2019

BeejReef said:
The little I know comes from binging the BRS video series.
Based on it, I heat and mix my saltwater for 24-48 hours and then just let it sit without further mixing or heat.
The night before a water change, I turn the pump and heat back on, do WC, then off again.

Aluminum is a common complaint. Did find a metal hose clamp on my mix-bin pump (since removed). Can't say if that was the culprit or not bc have not done follow up ICP yet.

My personal theory is that aluminum often is part of lighting and mounting assemblies.. DT lights, fuge lights, etc. The outsides may be treated, but a lot of them have cooling fans that blow all the internal corrosion all over your sump or DT.

Ever looked inside a fuge light? It's not prettty

I cringe at how much money you're wasting to re-heat that water. It's much cheaper to leave it continuously heating rather than starting back from 60 degrees.

AllSignsPointToFish · Nov 5, 2019

Hallowhead said:
I cringe at how much money you're wasting to re-heat that water. It's much cheaper to leave it continuously heating rather than starting back from 60 degrees.

We could calculate that if you're really interested

Hallowhead · Nov 5, 2019

AllSignsPointToFish said:
We could calculate that if you're really interested

I am not interested as I know it to be true.

AllSignsPointToFish · Nov 5, 2019

Hallowhead said:
I am not interested as I know it to be true.

LOL. It's probably not as bad as you think

BeejReef · Nov 5, 2019

Hallowhead said:
I cringe at how much money you're wasting to re-heat that water. It's much cheaper to leave it continuously heating rather than starting back from 60 degrees.

I hadn't thought of that. 3/4 seasons, the basement is a pretty stable mid 70's, but it is cold in the winter.

homer1475 · Nov 5, 2019

I leave my mixing pump, and subsequent PH in my barrels on. We constantly agitate our tanks water, so why not. Really only leave them on because I usually forget to turn them off.

Hallowhead · Nov 5, 2019

AllSignsPointToFish said:
LOL. It's probably not as bad as you think

Think of a hairdryer for reference, heat exchange draws a tremendous amount of power. When you turn a hairdryer on the lamps & lights dim for a short second as it's drawing a large amount of power... now try leaving that on for several hours to raise a 55 gallon brute can to 78 degrees..

AllSignsPointToFish · Nov 5, 2019

Hallowhead said:
Think of a hairdryer for reference, heat exchange draws a tremendous amount of power. When you turn a hairdryer on the lamps & lights dim for a short second as it's drawing a large amount of power... now try leaving that on for several hours to raise a 55 gallon brute can to 78 degrees..

It's not quite the same, though, because with the hair dryer you are changing the state of the water in the wet hair from a liquid to a vapor (sensible heat plus latent heat). In addition to that, people want to dry their hair relatively quickly and a lot of the warm air is lost to the room, increasing both the inefficiency and power requirements for that applicaiton.

In the water tank, you're only raising the temperature around 20°F (sensible heat only), and the heat transfer is nearly 100% efficient for an immersion heater.

AllSignsPointToFish · Nov 5, 2019

Put a different way, if you run a 300W heater for 2 hours continuously, you will use 0.3kW*2hr or 0.6 kWh. At $0.10/kWh, you just spent six cents

Hallowhead · Nov 5, 2019

AllSignsPointToFish said:
It's not quite the same, though, because with the hair dryer you are changing the state of the water in the wet hair from a liquid to a vapor (sensible heat plus latent heat). In addition to that, people want to dry their hair relatively quickly and a lot of the warm air is lost to the room, increasing both the inefficiency and power requirements for that applicaiton.

In the water tank, you're only raising the temperature around 20°F (sensible heat only), and the heat transfer is nearly 100% efficient for an immersion heater.

I wish I had a watt meter to further test this. For me.. being that my mixing station is in my garage and the ambient temp is much colder than room temperature it is much cheaper to keep it heated

BeejReef · Nov 5, 2019

Bossman said:
This is something I wasn't aware of. Why does the salt need to be agitated once it's already mixed? I use Red Sea Coral Pro and once it's mixed I shut off the pump. Usually use it the same day, but I have left it for days with just the heater running before I use it.

Don't know definitively. Just seems like a good practice to at least swish it around before adding to the tank. Is stratification real?