Tds meter rodi question

[krv]

Just got my first TDS meter in. Its the HM Digital TDS-EZ. I tested my tap water and it says 88. After carbon and prefilter it says basically the same, 86-88. After the membrane it says 3 and after the DI it says 0. Ive been having bright green and dark brown slime algae/cyano problems, so i wanted to check my water quality. The RODI has been set up and used bi weekly for about 4 months. If my tap TDS is already so low, should i expect the prefilters to drop the TDS much more than this? I think its about time to replace those cartridges anyways. My first question would be, should i trust this brand new factory calibrated TDS meter or recalibrate it with the NaCl solution it recommends and test again? My tank is a little over 3 months old, i dont believe i overfeed.

 

Nitrates: Always 0

Phosphates:0

 

I have 2 juvenile clowns and 2 young blue green chromis. Also, a cleaner shrimp, 7 nassarius snails, 8 or so hermits, and about 4 astrea snails. And a couple turbos i picked up to help with the algae. However they don't  touch anything on the sand, just the rocks and glass.

 

I use a pipet to feed the fish about 1/2 a cube of thawed and rinsed frozen mysis every 2 days. I have stopped feeding flake as of a couple weeks ago . If i go by the "what they can eat in 5 minutes" or even "what they can eat in 2 minutes" rule, they can eat more than a half cube. These 4 fish and my cleaner can eat almost a whole cube without getting full. Am i feeding too much?

 

I had mad diatom issues until probably a week ago, so i got a phosban reactor which has been running for about a week and a half. However my phosphates have always registered zero with my API kit. I was hoping that the phosban reactor would help with silicates if they were my problem. It seemed like after cleaning up my diatoms, as soon as i did a water change they would come right back (pre Phosban reactor).

 

The diatoms seem to be gone after installing the phosban reactor, but as of 2 days ago i've been "lights out" in hopes of clearing up the cyano but its taking its sweet time.

 

Anyone have any ideas? I had hair algae at first, then diatoms, now i'm dealing with the cyano. Is this just due to the age of my tank or is it something else?

 

BTW i've got 1000 GPH of flow from 3 separate powerheads in the display and its a 50 gallon.

Thanks

[krv]

bump

[AZDesertRat]

Prefilters and carbons have very little to absolute no effect on TDS. Remember we are talking about dissolved solids, things that are solutes. TDS measures in the 0.0001 micron range. The prefilter is rated in microns like a 10, 5 or 1 micron filter so it removes TSS or suspended solids, particulates and if it is a very good filter it may help with colloidal materials, things in the 1 micron to actually visible with the naked eye range like silt or sand.

 

The carbon block adsorbs chlorine and some organics so may have a very slight effect on TDS but water does not generall contain much organics so thats the couple ppm TDS reduction you may see. The average chlorine residual is maybe 1 or 2 ppm so it will drop the TDS about that much.

 

DI resin is what filters the phosphates and silicates out of the water and just like filters some resins are much better than others. I like the Spectrapure SilicaBuster DI resin as it is custom blended specifically for reef tanks based on years of testing. Down towards the bottom of the page here on sale:

http://www.spectrapure.com/email/customer-...eciation.html#1

 

 

That being said you want to use the best quality prefilters and carbon blocks you can find, some ar about as effective as a screen door while others get down in the sub micron ranges like 0.5 or 0.2 microns and do an excellent job of protecting the carbon block so it does not have to act as a secondary prefilter which plugs the billions of tiny pores and render it useless for adsorbing chlorine which is its job. Try to stick with a 1 micron or less prefilter and an absolute rated one is even better. For carbon most of the better RO/DI vendors use a 0.6 micron Chlorine Guzzler carbon block which is very effective at both chlorine and the chlorine portion of chloramines when it is protected well with a good prefilter.

 

 

While I like and use HM Digital TDS meters myself, the TDS EZ is very low end and not one I recommend.

As you can see in the chart here, it is not temperature compensated so is not as accurate and it does not measure and display temperature either. Anoter drawback is itsaccuracy is only 3% +/- of full scale compared to the others at 2%.

http://www.tdsmeter.com/img/selectionguide.jpg

 

My recommendation for an entry level meter is the TDS-3 and I use the COM-100 myself along with two of the DM-1 dual inlines which I use as a rough guide or quick glance type meter, the COM-100 is extremely accurate and 10x more sensitive than the others so is good for low range measurements like RO and RO/DI water.

 

Phosban and all GFO products do not work overnight, they depend on multiple passes or slow continous flow through the media over a long period of time. Start with no moer than half the recommended dose for your system size and change it frequently in the beginning for best results.

[krv]

Thanks! I'll look into getting a better TDS meter, and give my reactor a little more time.