Whats the best reverse osmosis filter?

So I'm looking to soften my water in my fish tank and I've been told that one of the best options for this is to use a reverse osmosis filter however I've noticed that they can be either quite pricy or dirt cheap so I'm not entirely sure which filter is good and not overpriced.

 

Depends on your needs and budget. There are only 2 or 3 manufacturers of the actual reverse osmosis membranes anyway, that have little to no difference in price, properties and quality. So the parts themselves have no impact on your decision.

Do you need a fixed installed one or want a "mobile" (connect to tap on demand) one?
What amount of gallons per day do you need? (Also determines the speed.)
Does your tap have enough pressure or would you need an extra pump and manometer?

I would consider all these factors. And maybe some more.

 

Depends on your needs and budget. There are only 2 or 3 manufacturers of the actual reverse osmosis membranes anyway, that have little to no difference in price, properties and quality. So the parts themselves have no impact on your decision.

Do you need a fixed installed one or want a "mobile" (connect to tap on demand) one?
What amount of gallons per day do you need? (Also determines the speed.)
Does your tap have enough pressure or would you need an extra pump and manometer?

I would consider all these factors. And maybe some more.

Well unfortunately I've never used a reverse osmosis filter so I know very little about them so I just assumed that due to their size they worked just like a normal internal filter which softens the water however it seems that I'm sorely mistaken

 

The way they work:
(Preferably cold) water is pumped into the unit (either by the tap pressure or with an extra pump), first going through a mixed-bed sediment filter to remove particles of solids, then it goes through an activated carbon cartridge to remove organic chemical impurities (like residue of meds) and then through the actual membrane that filters out most anorganic ions like calcium, magnesium and the like. After that it may either just go to the output, another activated carbon cartridge or a De-ionizer to remove every last bit of ions.

The membranes are rated by the volume they can process in 24 hours. Usually you start at 190 GPD going up to 750 GPD.

What amount of RO water would you likely need per week?

 

Well I will likely only need 10 gallons a week since I only have one tank that I'm planning to use it on.
P.S do the filters have a relatively short life time

 

Well I will likely only need 10 gallons a week since I only have one tank that I'm planning to use it on.

Then a small 190 GPD unit is more than sufficient. I also have one in that range and I also need about 40-50 liters a week (waterchange + top-of).
Going by average prices for storebought distilled water a cheap unit should pay off within 1-2 months.

P.S do the filters have a relatively short life time

The carbon and sediment filters should be replaced every 6-12 months depending on how much you use the unit and how many impurities (e.g. nitrate/chlorine/chloramine) are in the source water. In small, cheap units you usually pay about 10-20,- for each.
The membrane has to be replaced at least every two years. A new membrane costs about 25-30 bucks on average. Interestingly the longer it is in use once you turn on your tap, the more efficient it gets. Using cold water and flushing the membrane regularly can prolong the livetime by up to 9 more months. As with the other filters the more impurities the shorter the life time. So water with high hardness (GH/KH > 15°) will wear out and clogg the membrane faster.
Please be aware I'm thinking of Euros when talking about the prices.

 

Then a small 190 GPD unit is more than sufficient. I also have one in that range and I also need about 40-50 liters a week (waterchange + top-of).
Going by average prices for storebought distilled water a cheap unit should pay off within 1-2 months.


The carbon and sediment filters should be replaced every 6-12 months depending on how much you use the unit and how many impurities (e.g. nitrate/chlirne/chloramine) are in the source water. In small, cheap units you usually pay about 10-20,- for each.
The membrane has to be replaced at least every two years. A new membrane costs about 25-30 bucks on average. Interestingly the longer it is in use once you turn on your tap, the more efficient it gets. Using cold water and flushing the membrane regularly can prolong the livetime by up to 9 more months. As with the other filters the more impurities the shorter the life time. So water with high hardness (GH/KH > 15°) will wear out and clogg the membrane faster.
Please be aware I'm thinking of Euros when talking about the prices.

Ok cool just two more questions one, should I steadily intro duce the water or should I just dump it in as soon as I collect it.And two should I just outright ditch tap water in favor of tap water

 

should I steadily intro duce the water or should I just dump it in as soon as I collect it.

I usually take one day every two weeks and bottle it into 5l canisters, ending up with what I need for 2 50% waterchanges and top-of over the weeks. When doing a waterchange I fill some into a kettle, the rest into a bucket and I use a dive pump to add it to my tank. As the RO is pretty cold (16-20°C) even after a week in the canister I add half to a full liter of boiling RO from the kettle to the bucket bringing it to my usual 25°C.
In my opinion it's best to have some kind of storage container or canisters so you can add it quite quickly, as depending on the speed of the unit it can take hours to fill the tank back up. My 190 GPD unit takes about 50 minutes for 5 liters, say you do a waterchange and have to fill up 40 liters you are looking at 7.5 hours until the tank is full. Best to have the stuff prepared in advance. As it is basically pure water it can be stored for weeks or even months without problems in an airtight closed container.

And two should I just outright ditch tap water in favor of tap water

Depends.

If you keep softwater fish (like many tetras, rasboras, angels, dwarf cichlids, corydoras, loaches or plecos) you can go 100% RO and don't even have to remineralize and no need for dechlorinators. But to stabilize pH in the necessary low range (5.5-6.5) you will be dependent on adding tannins. But botanicals are at least dirt cheap and in fall you can collect leaf litter yourself.

If you have invertebrates (snails, shrimp) and/or hardwater fish (livebearers, central american cichlids, rift lake cichlids, rainbows), you will have to remineralize all the time, which can become quite pricey over time. You could also cut tap with RO, which means, while you safe money on remineralizing stuff, you still need water conditioners.

 

do you have a local fish store nearby? Those often sell jugs of RO for a fair price, and it's a good option if you don't need that much RO every week

 

do you have a local fish store nearby? Those often sell jugs of RO for a fair price, and it's a good option if you don't need that much RO every week

While this is an option driving around for this and maybe sometimes having neither time nor money for this can lead to more inconveniences (and longterm also costs) than necessary. It also makes you dependent on that source. Just saying.

In the end the OP has to decide.

 

do you have a local fish store nearby? Those often sell jugs of RO for a fair price, and it's a good option if you don't need that much RO every week

Yeah they do but it's rather tedious to go out and buy it. So I'd much rather prefer to just make the RO water myself
With that in mind is there a specific filter you'd recommend

 

With that in mind is there a specific filter you'd recommend

As I likely live one whole continent over and we have completely different brands... Not really. I have heard of a unit called "RO Buddy" which is basically identical to my unit. If it costs between 60 and 100 bucks you are in the safe zone.
The model should include 1x activated carbon, 1x sediment filter and 1x RO membrane. That's all you need to look for.

Doesn't need a power outlet, manometer (pressure meter), pressure punp or anything like that.

Edit: Make sure you have sufficiently sized canisters or containers to store the water in.

 

Ok thank you I'll check it out.

 

Good luck. You know what you're looking for, as long as the model fulfills the requirements and has a passable price you're all set.

Oh, one more thing: The models that are just connected to the tap sometimes need an adapter, you get those for a buck or two at the hardware store, so safe the money buying that part from the manufacturer they often offer these for 2-10x what you pay at the hardware store.

 

Good luck. You know what you're looking for, as long as the model fulfills the requirements and has a passable price you're all set.

Oh, one more thing: The models that are just connected to the tap sometimes need an adapter, you get those for a buck or two at the hardware store, so safe the money buying that part from the manufacturer they often offer these for 2-10x what you pay at the hardware store.

I actually just have one more question should I be prepared to remove some of my fish. I have 7 CPDs, 5 embers, 4 cards, 1 guppy, 1 pleco, and 1 honey gourami

 

Only the Guppy will have trouble in soft and acidic water. The rest should manage. All of them occur in pH below or around 6 in nature. Make sure to slowly change the parameters.
4x 25% waterchanges every other day over the course of a week is ok. Each waterchange remove 25% and add temperature matched RO instead. After the 4th waterchange you basically have converted the water to 100% RO.

While doing so add about 1-3 (depends on the size) IALs over the course of the week with each waterchange. You will see the pH dropping slowly over that week, with enough tannins from the leaves you should reach about 6.5 by the end. After that it will slowly go down to stabilize to 5.5. After the switch to RO add about 500ml of IAL and/or alder cone extract with each waterchange.
And yes, the water will stay stained and tinted. No way around this. May lead to you having to switch out some plants at some point.

One more: When you decide to do this, you will have to stick to the RO water. If you want to go back to tap you have to do the same week-long acclimation process in reverse.

 

Why do I have to add the leaves and/or cones

Why do I have to add the leaves and/or cones

Edit: I know that they contain tannins I'm asking about the relevance of the tannins

 

Edit: I know that they contain tannins I'm asking about the relevance of the tannins

Simple. As RO has no KH (which stabilizes pH around and above 7), you need another way of buffering pH. Tannins do this in the low pH range of 5 - 6.5, usually stabilizing around 5.5. Which is basically the range of the fishes habitats in the wild.

Maybe read up on that on Tannin Aquatics. (No you don't have to buy there, botanicals can be acquired far cheaper. But their blog "The Tint" is a great resource of information.)

 

Do think that my fish would breed in those conditions

 

The embers and the CPDs probably. For cardinals you would have to go further down with pH (about 4). In community settings successful breeding, especially with egg scatterers is unlikely.

 

Ok well I just have more question(I apologize for the relentless question asking) but though I doubt it is there a tannin alternative that won't tint my water

 

It's fine. I rather have somebody ask me a hundred questions instead of somebody running off to do/buy anything before I even finished explaining.

Yeah, no alternatives, sorry.

Either KH, requires regular addition supplements if you have a target reading for KH/GH or limestone and crushed coral, but those will saturate the water to liquid rock hardness-wise and raise your pH over 8, limits you to hardwater fish and certain inverts.

Or tannins, requires addition of botanicals and/or peat, pH stabilizes in a certain range below 6, limits possible inverts and completely excludes hardwater fish.

No third option, sorry.

 

you can go 100% RO and don't even have to remineralize

Full RO right from the start or through partial water changes? I was always told that if I dump a fish in straight RO or distilled it will leech minerals from the fish, potentially causing them lethal neural issues. So I won't fry fish that way and have been careful for no reason?
If you can just dump a fish into pure RO/Distilled with no issue I have been spreading the bad info I received to others.
I know for shrimp I had to remineralize which you already covered. I still have a bottle of SL Blue Aqua Wizard siting on my shelf since I'm out of the shrimp game.

Depending on where you live (humid is good) and what you want to keep, you can also consider a dehumidifier for distilled instead of RO. I won't swear the water is copper free, though ~0 TDS is not much if it is copper. A ~500sq foot dehumidifier is about the same price as an RO Buddy on Amazon.

 

Full RO right from the start or through partial water changes?

I anwer by quoting myself:

Only the Guppy will have trouble in soft and acidic water. The rest should manage. All of them occur in pH below or around 6 in nature. Make sure to slowly change the parameters.
4x 25% waterchanges every other day over the course of a week is ok. Each waterchange remove 25% and add temperature matched RO instead. After the 4th waterchange you basically have converted the water to 100% RO.

While doing so add about 1-3 (depends on the size) IALs over the course of the week with each waterchange. You will see the pH dropping slowly over that week, with enough tannins from the leaves you should reach about 6.5 by the end. After that it will slowly go down to stabilize to 5.5. After the switch to RO add about 500ml of IAL and/or alder cone extract with each waterchange.
And yes, the water will stay stained and tinted. No way around this. May lead to you having to switch out some plants at some point.

One more: When you decide to do this, you will have to stick to the RO water. If you want to go back to tap you have to do the same week-long acclimation process in reverse.

I was always told that if I dump a fish in straight RO or distilled it will leech minerals from the fish, potentially causing them lethal neural issues. So I won't fry fish that way and have been careful for no reason?

Well, without acclimation I wouldn't put fish in RO. Also be aware hardwater species (listed some of those in a post above) will not be able to acclimate. Only softwater species can work with this.

If you can just dump a fish into pure RO/Distilled with no issue I have been spreading the bad info I received to others.

As said above: Acclimation is necessary. E.g. when I got my current group of Pencilfish I acclimated them with the cup method for about 2 hours and then put them in. Only one loss out of 12 since (got them 07/27/21) and the fish are thriving.

you can also consider a dehumidifier for distilled instead of RO.

Rather not, as there are still particles from the air in it, which e.g. can include room sprays or cigarette smoke. Also the amounts these units produce are miniscule in comparison what you need for a waterchange.

I won't swear the water is copper free, though ~0 TDS is not much if it is copper.

Copper is no problem when using an RO unit and to make absolutely sure a DI-filter-stage would remove any copper left. Usually there shouldn't be any.

 

Even if you only need 10 gallons a week. Don't forget these small units give you RO pretty slowly. It depend also on how fast you want those ten gallons. The units will tell you how fast it filters too so just pay attention to that.
The under sink unit I have could probably deliver 10 gallons in about 20 minutes but it would be the longest 20 minutes of my life waiting for it. lol
I got a Water Drop unit, it's pretty cool because it has a pump not a tank, it takes up much less room under the sink. Also, the filters are very easy to change. I haven't had it very long so I can't say how it will hold up or how often the filters will last but so far so good. I just use it for top off so far. https://www.amazon.com/Reverse-Osmosis-Water-Filtration-System/dp/B08746M1NX/ref=sr_1_7?crid=2U91CN0BO5VEH&dchild=1&keywords=ro+water+filter+system&qid=1634842757&qsid=146-9146678-3741059&sr=8-7&sres=B00I0ZGOZM,B00J2DGTD8,B08746M1NX,B005LJ8EXU,B07F71QR5L,B07P1XFYJP,B00HRHHFPW,B08746G2XX,B083DFW1QS,B004S7TAK2,B083P4HZPD,B07FSWPT5P,B01N0OERWZ,B07Q47KNMT,B00PCRSD7I,B00SGGT14Q,B003XELTTG,B07M9CPCPT,B01MUBQIKT,B00MU20LN2&srpt=WATER_PURIFICATION_UNIT
like this:

 

Even if you only need 10 gallons a week. Don't forget these small units give you RO pretty slowly. It depend also on how fast you want those ten gallons. The units will tell you how fast it filters too so just pay attention to that.
The under sink unit I have could probably deliver 10 gallons in about 20 minutes but it would be the longest 20 minutes of my life waiting for it. lol
I got a Water Drop unit, it's pretty cool because it has a pump not a tank, it takes up much less room under the sink. Also, the filters are very easy to change. I haven't had it very long so I can't say how it will hold up or how often the filters will last but so far so good. I just use it for top off so far. https://www.amazon.com/Reverse-Osmosis-Water-Filtration-System/dp/B08746M1NX/ref=sr_1_7?crid=2U91CN0BO5VEH&dchild=1&keywords=ro+water+filter+system&qid=1634842757&qsid=146-9146678-3741059&sr=8-7&sres=B00I0ZGOZM,B00J2DGTD8,B08746M1NX,B005LJ8EXU,B07F71QR5L,B07P1XFYJP,B00HRHHFPW,B08746G2XX,B083DFW1QS,B004S7TAK2,B083P4HZPD,B07FSWPT5P,B01N0OERWZ,B07Q47KNMT,B00PCRSD7I,B00SGGT14Q,B003XELTTG,B07M9CPCPT,B01MUBQIKT,B00MU20LN2&srpt=WATER_PURIFICATION_UNIT
like this:

This unit is very pricey when compared to that small RO unit and while it does have a pump I don't know if it's worth it

 

Even if you only need 10 gallons a week. Don't forget these small units give you RO pretty slowly. It depend also on how fast you want those ten gallons. The units will tell you how fast it filters too so just pay attention to that.
The under sink unit I have could probably deliver 10 gallons in about 20 minutes but it would be the longest 20 minutes of my life waiting for it. lol
I got a Water Drop unit, it's pretty cool because it has a pump not a tank, it takes up much less room under the sink. Also, the filters are very easy to change. I haven't had it very long so I can't say how it will hold up or how often the filters will last but so far so good. I just use it for top off so far. https://www.amazon.com/Reverse-Osmosis-Water-Filtration-System/dp/B08746M1NX/ref=sr_1_7?crid=2U91CN0BO5VEH&dchild=1&keywords=ro+water+filter+system&qid=1634842757&qsid=146-9146678-3741059&sr=8-7&sres=B00I0ZGOZM,B00J2DGTD8,B08746M1NX,B005LJ8EXU,B07F71QR5L,B07P1XFYJP,B00HRHHFPW,B08746G2XX,B083DFW1QS,B004S7TAK2,B083P4HZPD,B07FSWPT5P,B01N0OERWZ,B07Q47KNMT,B00PCRSD7I,B00SGGT14Q,B003XELTTG,B07M9CPCPT,B01MUBQIKT,B00MU20LN2&srpt=WATER_PURIFICATION_UNIT
like this:

Sorry, but that type of Unit is suited for someone with a whole fishroom of rare blackwater fish or a 1000 liter South American community but paying almost 900 bucks to do a 10 gallon waterchange each week is absolute overkill.

 

Sorry, but that type of Unit is suited for someone with a whole fishroom of rare blackwater fish or a 1000 liter South American community but paying almost 900 bucks to do a 10 gallon waterchange each week is absolute overkill.

900? It was like $350. Is my link messed up? It's a small under the sink unit. It is pretty slow too. It's the type most people buy for clean drinking and cooking water.
It's not near as slow as the RO buddy though that's for sure. 24 hours for 50 gallons it says.
To each his own.

 

You linked to a high end unit that comes across like the iPhone of RO units. Also by design.
I wouldn't drink too much pure RO that's not healthy. But it's really nice for coffee, tea and cooking.

 

You linked to a high end unit that comes across like the iPhone of RO units. Also by design.
I wouldn't drink too much pure RO that's not healthy. But it's really nice for coffee, tea and cooking.

Yes, agreed. Sense it has nothing in it I don't drink it, I drink regular water filtered at my fridge. I bought the unit to do top offs for evap of the aquarium. My GF thinks I bought it for her for cooking and such. ahahaha.
I may someday use it for aquarium fill, maybe half tap half RO, whatever I come up with when testing. I have read that disease causing bacteria don't thrive in saltless water, the reason black water fish like Discus do well in it. I don't think I would chance going too far with RO though.

 

The low pH and the low ion content is indeed the reason bacteria levels are very low in Blackwater. And why many fishes eggs can only develop in these conditions, as they always fall victim to bacteria otherwise.