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Steve175
07/05/2010, 10:59 AM
I have had a low-grade but frustratingly persistent algae problem despite sequentially adding all of the usual suspects (very oversized skimmer, large refug, large GFO reactor, new bulbs, heterogeneous CUC, and Vodka dosing; was considering Bio-Pellets but experience seems to be anything but uniform and Vodka really did nothing useful for my tank). This algae has limited coralline growth on my LR (although I am frequently scraping it off the glass).

Despite a 5 stage RODI w/ a booster pump, I have been suspect of my water. At times, I have tested my fresh SW mix and have found measurable nitrates (0.2) despite only 001 TDS and new filters. As my large system requires 6G per day of RODI for evaporative losses, I think that low-grade nitrates in the water may be of particular issue for me. Am now thinking that I may need to filter water into larger intermediate tank and then use a 2nd RODI system (Spectrapure has one that will give 1:1 product).

Anyone in the SPS world using well water? Am I being too neurotic? Any other ideas?

TIA, Steve.

HighlandReefer
07/05/2010, 11:21 AM
I'm not quite clear with your statement. :)

After your rodi unit your TDS reading is 001 & not zero?

Have you tested your rodi water for nitrate or just your freshly made salt mix?

Are your tank nitrate and phosphate reading zero?

Steve175
07/05/2010, 11:33 AM
RODI output TDS has always been 1 and never zero even with new filters (in fact, I change them the first time that I see a 2 and I added an additional prefilter that I change more frequently due to rapid gunk build-up).

Nitrate in system was high prior to adding Deltec AP1004 now consistently 0.02-0.05 by Salifert (never had an unmeasurable reading). Phosphate was also previously weakly measurable but consistently 0 since adding large GFO reactor; obviously I still have phosphate in system incorporated into algae.

Test for nitrate on pure RODI is not measurable but newly mixed and covered SW is consistently 0.02. I had assumed that the nitrate tests were not accurate on pure RODI due to either pH or salinity differences as they are designed for SW but that I never confirmed. Regardless, the measurable nitrate in fresh SW has been across multiple batches and multiple types of salt.

TIA, Steve.

HighlandReefer
07/05/2010, 11:43 AM
It is not unheard of despite the salt mix manufacturer's claims that there is some nitrate and phosphate in salt mixes. Personally I would not worry to much about what your salt mix adds as this is not much compared to what foods add to your system on a regular basis.

Many of the hobby grade TDS meters can't be calibrated. One thing you could try is buying some distilled water from the grocery and check the TDS on it. If you get a zero reading for the distlled water, then perhaps there is some problem with your RODI unit not being able to get pure water. In some cases adding a 2nd DI filter can help. Hopefully the distlled water reads 001 also, which would mean your TDS meter is off a bit and everything is fine.

As far as your algae problem, the algae is probably taking up the phosphate and nitrate when food is added. Reduced feedings to perhaps once every two or three days may help here along with reduced total amount of feeding depending on your fish. Keeping your tank clean of all depris by siphoning, removing the algae, running filter bags, cleaning your skimmer regularly will help. ;)

bertoni
07/05/2010, 03:32 PM
I'm not sure I'd trust distilled water to read 0 TDS. As carbon dioxide enters the water, it will raise the TDS, for example. There are various calibration solutions on sale that might be useful.

What is the TDS of the tap water?

Steve175
07/05/2010, 07:36 PM
Honestly do no think it is a husbandry issue: Feed sparingly and rinsed only every other day and do a 75G water change (~15%) every 7-10days (nearly automated).

Also, this system really shouldn't have algae: 300G refugium on a 220G with > 700# of LR and DSB in both display and refug. Deltec AP 1004 as above with LARGE GFO reactor and a large carbon reactor. Replacement water runs through large Kalk reactor.

Hadn't thought to confirm the TDS measurement given measurable nitrate in the freshly mixed SW but will (have a separate meter arriving in next few days).

Any other ideas? Where can I find calibration fluid?

Thanks, Steve

bertoni
07/05/2010, 08:08 PM
I think a number of stores sell the PinPoint solution, and cole-parmer.com has a good selection, too. I like the one-shot pouches for pH. They might offer them for TDS, too.

HighlandReefer
07/06/2010, 06:10 AM
Jon is right regarding the CO2 possibly interfering with your TDS reading in both rodi water and distilled water. :)

I re-read Randy's RODI article:

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

From it:

"Do not agonize over 1 ppm versus zero ppm. While pure water has a TDS well below 1 ppm, uncertainties from carbon dioxide in the air (which gets into the water and ionizes to provide some conductivity; about 0.7 mS/cm for saturation with normal levels of CO2, possibly higher indoors) and the conductivity/TDS meter itself may yield results of 1 or 2 ppm even from totally pure water by not being exactly zeroed properly."

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"Also, this system really shouldn't have algae: 300G refugium on a 220G with > 700# of LR and DSB in both display and refug. Deltec AP 1004 as above with LARGE GFO reactor and a large carbon reactor. Replacement water runs through large Kalk reactor."

FWIW, many species of algae can become pests in pristine natural reefs once they are introduced. So, difficultly of controlling your algae problem can depend on the particular specie you are fighting. Unfortunately most hobbyists do not have the expensive equipment to detect very low levels of phosphate found in pristine reef waters of about 0.005 ppm. Reducing your phosphate level can be one of the most effective weapons when trying to fight algae problems. One reason to run GFO and change it out fairly frequently. Nitrate does not seem to effect algae as much as phosphate. There have been many examples in research where higher nitrate levels, within reason, do not seem to cause algae problems. Also the total dissolved organic content can contribute to algae growth as well as higher phosphate levels. This is a good reason to run GAC and change it out perhaps every two weeks while fighting an algae problem. Using low phosphate foods can help as well. Running filter bags or perhaps a diatom filter can also help in reducing the phosphate available to the algae.

I have noticed that some of the hobbyists have noted that their algae problem was greatly reduced and/or eradicated after using some of the solid carbon dosing products for a while, like the NP BioPellets for one. One hobbyist claimed it eradicated his bryopsis, which is certainly a difficult specie of algae to control. These are encouraging reports which only time will tell down the road as more hobbyists begin to use these products. ;)

mnchartier
07/06/2010, 10:21 AM
Do you have a filtration system setup on your well? I have a well and SPS, direct from the well I was getting a TDS of 319, after my house filtration system (before RODI system) I was getting 39 TDS and 0 out of RODI. If you don't have a filtration system on your well you may want to send a sample out to a lab to test it to see if you need one. There could be something in the well water that is causing the issue.

We had a large amount of iron in our water.