# RO/DI vs. Nitrate Filters - opinions, please!



## hisplaceresort1 (Mar 10, 2014)

Hi!

I admit that I have a ridiculously overstocked tank - 42 fish (39 cichlids, mostly mbuna, 3 catfish) in a 75 gallon tank. Saving pennies for the upgrade! My fish look really good, and are healthy, but it's a ton of extra work with this kind of a stocking level!

My biggest problem, obviously, is the nitrates...

1.) I've had no luck recharging Purigen. It still smells like bleach when I'm done. If I didn't use Purigen, I couldn't go 3 days without a water change. When you use as much of it as I do, it gets really expensive. I probably use $50/month, and I buy in bulk.

2.) I do 2 back to back (Sunday & Monday) 60-70% water changes to get my Nitrates back down to 5ppm. By the following Sunday,they're back to at least 25-30ppm if my Purigen is relatively fresh, and 40ppm or worse if not.

3.) I run 2 ea Cascade 1500's for about 700+gph filtration. I use Seachem Stability (which has anaerobic bacteria for nitrates) and in those canister filters I use every biomedia (Biohome, Matrix & Fluval rings) some of which are supposed to be able to house that anaerobic, nitrate-eating bacteria, and I still have problems.

So, I began to read some about RO/DI products. What puts me off about those is that DI water itself is actually used in many industrial applications, and by law one is required to mark it as not safe to drink! OK... and... we're gonna put fish in this? So out of curiousity, I then went to the reef forums to see if those fishkeepers are actually _drinking _any of this stuff, and they ALL say they take their drinking water out of their system _before _it hits the DI portion of their filtration setup... in other words, many of them actually drink RO water out of their home systems, but absolutely do not drink RO/DI water.

And even the RO water by itself... the resulting water is supposedly kind of soft, and it also removes minerals with the bad stuff... Well, fish _need _minerals, so to my thinking, this doesn't seem like the optimal solution...

Next, I started reading about the denitrators - like Aquaripure. I'm not looking for a specific product review, this discussion could be about any brand to keep the moderators of the forum happy...

Sorry for rambling, but here are my questions to those who use either system for their cichlids:

1.) Water changes would still seem necessary to replenish minerals or other things we don't typically monitor. How often do you still change your water and how much? And how does that compare to before you installed your unit of choice?
2.) With either type of system, does it actually _replace_ your canister filters/refugium filters/HOB's, or do you run both?
3.) What is the maintenance for either of these systems like, and about how $ do you spend maintaining them?
4.) Do you add anything to the water to replenish minerals with either system?
5.) Is there anything else one should consider?
6.) As far as general sizing guidelines, I would guess that someone like me, with a heavily overstocked 75 gallon, should probably double the size of the system?

Thanks for your help!


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## BDASTRK (Dec 12, 2014)

This is quite the familiar situation you have here, I have been in your shoe's and all I can tell you is my experience and that is with the Aquaripure De-Nitrate filtering system. I learned about this from one of the smartest Aquarium fish guys I know his name is Shane. He owns a LFS in the Portland Oregon area and he also has a fish maint division that cares for about 30 large aquariums. The Aquaripure filter took my overstocked 70 to 90 Peacocks and hap tanks from 100 to 180 PPM nitrate level down to 20 PPM nitrate level...................However it took some time for this to happen, this doesn't happen over night, it must get established and it took about 8 weeks before it really dropped the Nitrate level down to a manageable level. Now I have heard by many people on here that you want to keep your Nitrates at a 20 or less PPM...................But I can tell you from experience that I had well over 80 PPM on a ongoing basis for well over 10 years with very little loss so I don't really buy into the who low nitrate thing being below 20 PPM. Much more important in Salt water then fresh, however I do like a very busy tank and I wanted to play it safe and the Aquaripure allowed me to do that very thing.

The maint is simple you never have to open it up to clean it, all that really has to be done is you inject a small amount of Vodka..............that's right Vodka into the canister via the syringe port 2 times a week. I do this with my water changes, as I still do them but at a much lesser rate then before. If getting your Nitrates to a low level is something you desire, then I cant recommend anything else based on experience then a Aquaripure................It does work well.

Just so you are clear on what my system is I run the following

1) Wet Dry with a 5 gallon bucket full of bio Balls
2) Little Giant 4 mdQ filter to recirculate the water running through the wet dry
3) Ocean Clear Canister filter with foam inserts
4) Ocean clear Carbon filter media only
5) Little Giant Te5 running the two ocean clear filters
6) UV sterilizer 40 watt
7) Aquaripure Large De-Nitrate filter

The tank is a 150 and the water per gallon are roughly 3800 GPH circulating the tank. If you where to buy a aquaripure I would recommend a large unit, they are not much more expensive and you will have a little more room for error. Hope this helps and good luck!


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## hisplaceresort1 (Mar 10, 2014)

Thanks, BDASTRK! That is a definite +, hearing about someone with cichlids successfully using one of these types of units. 
I was a bit skeptical, because most of the testimonials are reefers and salt, which seem to be relatively low bioload.
Thanks for the detail. (looking at the Big Kahuna - not much more money and will eventually get bigger tank, too.)
So, I assume you still do some partial water changes - or just top offs now? Do you use any other "additives" like Seachem Stability, Cichlid Trace (for minerals) or anything else now? Thanks again!


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## BDASTRK (Dec 12, 2014)

My water changes are about 30 to 40 gallons 2 times a week, once this batch of fish get all above 4" I will change water every 10 days, but there are a few in there that are a little small and I tend to see a rapid growth rate with smaller fish when water is changed more often. I dont add anything but marine Buffer and some Salts that is it and prime of coarse


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## BDASTRK (Dec 12, 2014)

The other thing I want to mention is the Di/RO system, I am no expert here but my travels have essentially gained me this knowledge.........R/O systems dont produce a lot of water, so water changes running threw the R/O will be a little more challenging. I plan on using an R/O system on my new 800 gallon tank, However I will be using it as a overflow system. The main problem with this is the expense, water here in the NW is crazy expensive for whatever the reason "We are not short of it by any means" yet I get $125.00 a month water bills in the summer because of my Sprinkler system which only comes on 1 time a day for 30 min.

The intent of the overflow I believe will allow me to not have to do water changes EVER. What has held me back from doing this typ of system has always been the $, but at the end of the day I think this is the best way to go for a larger aquarium. Still have not figured out how I am going to clean this 14'L x 2.5"D X 40"T tank though!

Might have to hire a service to do it, 40" tall sure makes getting to the bottom rather tough, my 28" tall 150 sucks sometimes. Looks like some long hand tools will be a must.


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## OllieNZ (Apr 18, 2014)

RO/DI is for filtering water before you put it in the tank and nitrate filters work in the tank system. If you're happy with your tap water then RO/DI is a waste of time and money. The reason you have to mark DI water not safe for drinking is that with zero mineral content it will strip minerals from your body. Fish have developed a method of dealing with this (osmoregulation) and some species will happily live in waterways with zero mineral content. Unfortunately (or fortunately depending on how you look at it) mbuna require mineral content in the water. I have no experience with nitrate filters I've always preferred plants. In this situation emergent plants make excellent nutrient scrubbers. The other thing to consider is that water changes keep all waste products including ones your test kit won't measure in check.


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