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.....

 

[fullinfusion]

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?