TDS readings

[m2434]

Originally posted by AZDesertRat
6 TDS after DI can very well be phosphates, silicates or nitrates as all three are weakly ionized and released by exhausted resin. TDS meters may not even register some levels of each but a conductivity or resistivity meter would.

The key is change the resin when you first begin to see anything other than 0 TDS.

Fair enough, now the question is, as Alaska_Phil pointed out, what to do... Cyano, shouldn't care about silicates and can often fix N2, so wouldn't be expected to be particularly N limited. I would think the phosphate reactor on the way, would be a good start. You may have to change it out often if there is significat P. Also I find with cyano, a turky baster and wet skimming works wonders once you limit the nutrient source.

[dead beat reef]

Test ro/di water just before you use it. If it is not
.001 to .003 no good. Could be the filter. Could
be what the water is kept in. PM the the D Rat
he knows. If you get .00 reads an still have red
or hair. I can help. all the best dbr

[aquadog11]

Anyone know the best temprature to make RO/DI water?

[Randy Holmes-Farley]

I agree that 0 is the best and it is what we all should strive for... but do you really think this guy should dump a whole 50g tank because he is at 6?

If that is a container of RO/DI, I sure would. If you have chloramine in the water, the cartridge may be releasing a lot of ammonia. I accidently let a DI go to long, and when I made limewater with it, I could smell the ammonia across the room.

That said, I think cyano is not all that likely to be caused by things in the RO/DI. The amount of nutrients added in food is likely a lot larger. Increased skimming, carbon, and other nutrient export is the way to deal with cyano long term.

[gig]

my TDS got to 14 and I really started to get some disgusting grey stringy/cottony algae or something growing all over my tank. Needless to say, I'll keep my RO/DI in check from now on!

[Alaska_Phil]

Originally posted by aquadog11
Anyone know the best temprature to make RO/DI water?

Most manufactures recommend about 75F. But my understanding is that it only effects the output rate from the RO membrane, not the quality of the water.

Phil

[Randy Holmes-Farley]

I discuss temp effects a bit in the article I posted:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

from it:

Various factors, such as temperature and pressure, impact not only the flow rate through the membrane but also the purity of the resulting water. Lower temperatures make the water more viscous and less likely to flow through the small pores, reducing the production of purified water. The effect of temperature on purity is much smaller, with purity decreasing slightly at higher temperatures. Higher line pressure across the RO membrane results in higher rates of production and quality, although a pressure that is too high can damage the membrane. Any backpressure on the effluent will degrade performance. Very high TDS (total dissolved solids) in the source water also leads to higher osmotic backpressure, reducing the membrane's effectiveness. As a rough guide, every 100 ppm of TDS produces 1 psi of osmotic backpressure.

[aquadog11]

I usually run my unit with just cold water but lately I came across something saying 60 something to somethig in Deg. A unit should run at.So what would be the best temp for A unit to run roughly?

[AZDesertRat]

77 degrees is what they are designed to run at. Most of us do not have 77 degrees especially in winter months but thye will work fine at lower temperatures. Do not try to mix hot and cold water using a faucet. Rember being in the shower and someone flushes the toilet and you get scalded? The same thing happens to your RO membrane and it melts. Russ over at www.buckeyefieldsupply.com has a really easy to use calculator at the top of his home page that gives you a very accurate estimate of GPD flows if you know your water temperature and pressure, give it a try. You can make up for colder water by increasing pressure with a booster pump or dual membranes if you have sufficient pressure.