Water changes- What is your method?

[Randy Holmes-Farley]

I got the idea from dialyseas hype. I do note that on the dialysis membrane spec sheets… different molecules diffuse at different rates…. and I am not sure if allowing equilibrium is the goal.

I have been hoping a nephrologist would chime in to explain what selective removal is and is not possible (beyond manipulation of the dialysate). Adjusting resistance on the ouflow of the ‘blood line’ greatly affects the product and waste ratio… as free water tends to diffuse really quickly into the tank.

I'm very familiar with such processes. My best real world invention is a phosphate binder for dialysis patients (sevelamer), and have worked on programs to bind phosphate or other problem materials in dialysis fluids during dialysis.

I assume that you are running new salt water through the tubing, not RO/DI the way dialyseas does?

If equilibrium is not reached, the concentration of toxins/impurities in the dialysate will be lower than the tank water.

Assuming you have new salt water on the inside of the tubing, then It is not possible to selectively remove nitrate to ever have a higher concentration in the dialysate than in the tank.

One can potentially have selective removal or retention (the opposite of removal) of phosphate by changing the pH in the dialysate compared to the tank, but that will also end up changing the tank pH and alkalinity and I don't think the dialysate can stay at a different pH or alk for long enough to accomplish that (since H+ and OH- and small counterions will quickly cross the membrane).

 

[FishTruck]

I'm very familiar with such processes. My best real world invention is a phosphate binder for dialysis patients (sevelamer), and have worked on programs to bind phosphate or other problem materials in dialysis fluids during dialysis.

I assume that you are running new salt water through the tubing, not RO/DI the way dialyseas does?

If equilibrium is not reached, the concentration of toxins/impurities in the dialysate will be lower than the tank water.

Assuming you have new salt water on the inside of the tubing, then It is not possible to selectively remove nitrate to ever have a higher concentration in the dialysate than in the tank.

One can potentially have selective removal or retention (the opposite of removal) of phosphate by changing the pH in the dialysate compared to the tank, but that will also end up changing the tank pH and alkalinity and I don't think the dialysate can stay at a different pH or alk for long enough to accomplish that (since H+ and OH- and small counterions will quickly cross the membrane).

Neat! Yes… regarding the management of hyperphosphatemia in kidney failure patients … there seems to be lots going on with dialysis run times ans other stuff which is out of my grasp.

I do run ro/di through the tubing - only because it is simple. Still trying to invent a scenario of selective phosphate / “waste “ / toxin removal to substantiate the dialyseas claim. I’ll post it if I find one. Also, I’m due for an ICP test. I’ll see how three years of dialysis is doing. Cheers

 

[Jeffcb]

38 Gallons in a Brute.....

 

[Salty_Northerner]

10% every week and no storage. Use Red Sea black bucket so once its clear and brought to temp in it goes.

 

[MECOMI]

First always advise the spouse or partner that you will be busy...very important

Started with a home depot 5 gallon bucket, Red Sea Blue, pump, RODI system, small heater, and mix for 2 hours for my Biocube 32. I used a 1 gallon pitcher to take 2.5 gallons out every week.

When i upgraded to a Red Sea Max S-500 and kept the Biocube i moved to a storage system. Two Brute trash cans, Standard Instant Ocean, External pump, RODI, bigger heater, and a very long hose to pump from the basement up to the two tanks. Best thing i ever did in the hobby so far besides the tank upgrade

Mix for 24 hours, heat when needed, change out approximately 8% water volume on Biocube (2.5 gallons) and RSM S500 (10 gallons) weekly. Use half inch hose syphon. I gave the pitcher back to the wife.

Repeat...

Later days,

B-Kind

 

[CoralB]

I pre make water in advance in 50 gallon container with heater and circulation. When I do my water change I siphon out 20% of the water from the tank weekly while siphoning 1/4 of the sand bed . Then pump new water back into the tank .

 

[Randy Holmes-Farley]

Neat! Yes… regarding the management of hyperphosphatemia in kidney failure patients … there seems to be lots going on with dialysis run times ans other stuff which is out of my grasp.

I do run ro/di through the tubing - only because it is simple. Still trying to invent a scenario of selective phosphate / “waste “ / toxin removal to substantiate the dialyseas claim. I’ll post it if I find one. Also, I’m due for an ICP test. I’ll see how three years of dialysis is doing. Cheers

OK, let us know if you ever measure phosphate or nitrate in the dialysate and find it higher than in the tank water it has exchanged with.

 

[FishTruck]

OK, let us know if you ever measure phosphate or nitrate in the dialysate and find it higher than in the tank water it has exchanged with.

Now you are teasing me - LOL - but not so fast! This is what I meant earlier by perhaps not wanting equilibrium to occur. In a dynamic state (non equilibrium), the rate of ion removal could produce a difference in the ratio of ionic diffusion into the dialysate. The goal - in my reef tank - would be to remove nitrate faster than the other anions, not to remove the maximum number of ions per unit time.

I agree that if we allowed equilibrium to occur, osmotic forces would overwhelmingly define the end result - and no scenario to expect selective nitrate removal is available.

Below, shows the decreasing concentrations versus time of various Cations and Anions in a vat of test salt water subjected to dialysis, using RO water as the dialysate. Ken Feldma's experiments published in reefkeeping magazine.

I am fishing for someone to educate me on how the findings below might be possible (or not). The author does admit that this might be due to inaccuracies in the measurement of nitrate. The hydrostatic pressure applied to the leaving tank water and the fact that we are perhaps running the system too fast to allow equilibrium, in my mind, makes it possible to selectively remove certain anions over others.

It's also notable that at 150 minutes... all the cations are gone but not all the anions. How to balance the charge?

 

[CamoFan]

I try to do a 25% water change (10gal) every week and a half on my 40 breeder.

 

[cooltowncorals]

I run a 2 gallon AWC using hydros on my 180 (I use high and low optical sensors) have been doing for 3 months no issues.

I use 2 500ml perilistic pumps on the hydros switches

I turn it off if I go on vacation and just leave the ATO on because I don’t want a crazy failure while out of town.

I have it set up to run when I’m at home at night.

 

[Randy Holmes-Farley]

I am fishing for someone to educate me on how the findings below might be possible (or not).

It's not hard to explain that data, but the explanation suggests it's a bad process to use to lower nitrate (IMO).

Dialysis membranes are made of lots of different materials with different properties, but in essence all of them separate on the basis of size/diffusion rate through small pores.

If you look at the published data for one type of separation membrane, RO membranes, for which there is lots of data on the ability of various ions to penetrate them, you can see that compared to the other ions tested in the paper, nitrate is among the easier ones to get through (that is, has a lower rejection rate):

Reverse Osmosis Rejection Percentages – Pure Water Products, LLC

Typical rejection percentages of various contaminants for a standard thin-film composite reverse osmosis membrane.

www.purewaterproducts.com

Advanced Water Systems - Reverse Osmosis Water Filtration, Water Filters and Water Softeners

Advanced Water Systems - Reverse Osmosis Water in Phoenix Arizona

www.advwatersys.com

https://www.researchgate.net/figure/Expected-rejection-values-of-nanofiltration-and-reverse-osmosis-membranes-on-ter-tiary_tbl2_322848705

Thus, in a test comparing say, chloride to nitrate, nitrate will be enhanced in the effluent.

However, two things happen in this process that, IMO, make it a much poorer choice than a water change.

1. Unlike a water change that helps drive ALL ions in the water toward the concentrations in the new salt water, this process skews all ions on the basis of their diffusion rate through the membrane, changing the composition toward larger hydrated ions that diffuse more slowly and away from faster diffusing, smaller hydrated ions.

2. If you use fresh water on the opposite side from the salt water, as suggested here, water will flood across from the fresh water to the salt water, diluting the aquarium water. That process will be much faster than the diffusion of ions which are much larger and diffuse more slowly (that's why an RO membrane is useful to purify water).

 

[William Toohill]

I have a saltwater pre heated barrel in the basement with a utility pump. I drop a small pump in the tank with a hose to my kitchen sink. Drain off 20 gallons and then use the pump in the basement with a garden hose to fill the tank back up with the preheated salt water. I used to do this every week.

 

[FishTruck]

It's not hard to explain that data, but the explanation suggests it's a bad process to use to lower nitrate (IMO).

Dialysis membranes are made of lots of different materials with different properties, but in essence all of them separate on the basis of size/diffusion rate through small pores.

If you look at the published data for one type of separation membrane, RO membranes, for which there is lots of data on the ability of various ions to penetrate them, you can see that compared to the other ions tested in the paper, nitrate is among the easier ones to get through (that is, has a lower rejection rate):

Reverse Osmosis Rejection Percentages – Pure Water Products, LLC

Typical rejection percentages of various contaminants for a standard thin-film composite reverse osmosis membrane.

www.purewaterproducts.com

Advanced Water Systems - Reverse Osmosis Water Filtration, Water Filters and Water Softeners

Advanced Water Systems - Reverse Osmosis Water in Phoenix Arizona

www.advwatersys.com

https://www.researchgate.net/figure/Expected-rejection-values-of-nanofiltration-and-reverse-osmosis-membranes-on-ter-tiary_tbl2_322848705

Thus, in a test comparing say, chloride to nitrate, nitrate will be enhanced in the effluent.

However, two things happen in this process that, IMO, make it a much poorer choice than a water change.

1. Unlike a water change that helps drive ALL ions in the water toward the concentrations in the new salt water, this process skews all ions on the basis of their diffusion rate through the membrane, changing the composition toward larger hydrated ions that diffuse more slowly and away from faster diffusing, smaller hydrated ions.

2. If you use fresh water on the opposite side from the salt water, as suggested here, water will flood across from the fresh water to the salt water, diluting the aquarium water. That process will be much faster than the diffusion of ions which are much larger and diffuse more slowly (that's why an RO membrane is useful to purify water).

Yep, thanks Randy... these are my observations and thoughts exactly.

The amount of freshwater that pours across the membrane back into the tank is shocking - and you can see it happening on the product flow meter in real time. This is managed by closing a flow valve on the product line. Since I can see the waste and product flow rates, I add resistance to the product line until I see the waste flow rate is slightly higher than the product flow rate. Thus, I can remove volume while maintaining salinity.

This allows me to add larger amounts of kalkwasser - beyond what is evaporated from the tank.

I run a pretty modest dialysis run each day, and it is clearly not overly removing nitrate, since my nitrates run between 20 and 40.

Besides producing no miracles in nitrate or phosphate removal - after three years - the dialysis and brine method stood up pretty well on my ICP testing and remains a fun alternative to water changes - for me.

 

[Randy Holmes-Farley]

Yep, thanks Randy... these are my observations and thoughts exactly.

The amount of freshwater that pours across the membrane back into the tank is shocking - and you can see it happening on the product flow meter in real time. This is managed by closing a flow valve on the product line. Since I can see the waste and product flow rates, I add resistance to the product line until I see the waste flow rate is slightly higher than the product flow rate. Thus, I can remove volume while maintaining salinity.

This allows me to add larger amounts of kalkwasser - beyond what is evaporated from the tank.

I run a pretty modest dialysis run each day, and it is clearly not overly removing nitrate, since my nitrates run between 20 and 40.

Besides producing no miracles in nitrate or phosphate removal - after three years - the dialysis and brine method stood up pretty well on my ICP testing and remains a fun alternative to water changes - for me.

Thanks for the update.

 

[MickeyCT]

We've been having a phosphate issue in the tank at home so we've been doing weekly water changes. My hubby has a nice setup in the garage with a 250 gallon tank of salt water with a pump to cycle it and pump it out. We connect the hose to the sump, open the valve, open another valve and the tank drains, then close both valves, hook the other end of the hose to the pump, open the sump valve and it refills the tank. It takes less than 30 mins to do a water change of about 100 gallons. For my work tank, I have a pump that I stick in the tank and fill a 5 gallon bucket, then put the pump in the fresh salt 5 gallon bucket and pump it back in, water change complete

@erin10885 - can you describe more about the setup in the garage? Pictures would be great. I'm in the middle of a project to move my sump to the basement and will be building a new mixing station. It sounds like you are using the same pump to drain the tank and refill the tank but without needing to move it. I'm hoping I can figure out a way to do that myself and hoping your description and pictures might help.