Reef nutrition

RODI Replacement Cannisters

MolaMola said:
My sediment and 2 carbons were less than two months old but I changed them because tap TDS was less than post-carbon. Unfortunately, I always mean to keep track of the volume of water processed but never do. Now, tap is 170 and post-carbon is 200. I was careful to rinse the carbon a lot, too.
Water filtration is always messing with me! Added a second DI canister as I think @Coral reefer suggested to pair old one with a new one. Got a second RO membrane to add to my getting-old membrane but haven't hooked it up yet. I think I go thru all my media too quickly. YEP = I need to measure how much water I process. I will consider the meters I have seen discussed in the forum so it actually gets done.
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ofzakaria said:
Ha ha got it.
Am gonna get out of this thread and gather my shattered dignity ha ha ha

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Haha, no worries man. Tough to communicate through writing sometimes. Thanks for helping. That’s what this club is all about.
 
sfsuphysics said:
The only way I can possibly think why your TDS is higher after is simply due to how the TDS is being read.

My first thought is swap the probes from before and after prefilters, make sure both are aligned in the same fashion with respect to the water they're going through.

My second thought is because TDS meters work on measuring conductivity perhaps when the water is "dirtier" it doesn't conduct as much, giving you an false positive... and a little googling shows this
"Since, activated carbon does not remove most inorganic compounds from water; TDS is not an effective way of measuring the product performance. In fact, carbon adds some inorganic compounds to the water. As water passes by carbon, trace amounts of some inorganic compounds dissolve in the water. These compounds can be potassium bicarbonate, sodium bicarbonate, calcium carbonate and carbon dioxide. Therefore, activated carbon can increase a measurement of the TDS. This effect is more pronounced with a new filter. As a filter is used this effect decreases because these inorganic materials are flushed out of the carbon. "
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Never knew this. Thanks.
 
So my usual plan:

Sediment prefilters are easy. When they look ugly brown, replace. Cheap anyway.

I measure TDS at output of RO unit.
When it bumps up to about 3, I replace it.
BUT : It starts out higher, run it for 15 minutes.

For DI resins, they are color changing, so easy to know when to replace.

For chloramines, which I have, I usually measure the "flush" water.
As you start each run, you should be flushing RO membrane.
Save a bit of that, and test with pool test kits. You can put extra drops in.
If it is not 0, replace carbon pre-filters.

I do measure final TDS output also. If it is not 0, something is really wrong.
 
I do want to emphasize: Crud can accumulate when RODI is idle.

It really helps to flush membrane for a bit when you turn RODI on.
Not just for membrane, but to get the crud out of prefilters.

Do not measure TDS immediately. It can be very high for a short time.
 
Rostato said:
I always here about this but don’t understand why it could be beneficial. You just going to flush it when you start it up anyway right?

Plus if my float valve shuts off my unit I can’t run it to flush it anyway...
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I don’t use float valve. Washing off whatever is stuck to the memrane before letting it sit for an extended period of times makes sense to me.
 
I use a Spectrapure unit with auto flushing.

Input before everything is 300+. After Carbon before membrane is slightly higher, usually just a a few points higher.

After membrane is around 4. After DI is 0.

I use 98% membranes from Spectrapure.


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Is it a spectrapure auto flush unit or other brand? And do you like it? I thought it was a cool idea, but I remember reading some negative reviews of whatever one brs sells.
 
Flagg37 said:
Can you buy the auto flush separately and just add it to any system? I use the RO part and use it for drinking water and then the DI just for the tank. Am I able to have it only auto flush when I use the DI?
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Not retrofitable. I had to buy a new unit even though I already had 1 or their manual flush units.

The RO Buddy from Aquatic Life has a booster pump as well as being an auto flush.


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