A Definitive Answer: Do You Need RO/DI Water for a Saltwater Aquarium or Reef Tank? 

This kind of stuff is so helpful. Love you guys and all your content. Keep it up!

Before I could afford a proper RODI unit, I used tap water for 5 years. Never did any testing, never had any problems. Even mixed SPS tanks did well with tap water. After changing to RODI water, there was no noticeable differences.... still not testing either 😅

With my first mixed reef tank I used well water heavy with lime. Best tank I ever had. The growth was insane.

Nice. Answers to everything as always. You guys are legends!

Well done Randy, very informative. Thanks

Fantastic information. Although I use RODI water it is great to know 100 reasons why I do! Thanks for that!

I live in Vallejo,ca Bay Area and the water quality is amazing with just some ions concentrated reef safe dechlorinator

the crazy variance in parameters and PPM for "tap water" is interesting to see- in NY our water is super clean- rodi filters last a really long time - and i know a local maintenance company that uses tap water lol

When I first started my reef tank, I wasn't too keen on spending $150+ for an RODI setup, but I didn't want to go the tap water and Prime combo. My solution was a distiller! You get EXTREMLY pure water from a machine that only costs around $100 and doesn't need you to buy filters. Obviously, distilled water is TOO pure, but it seems like the salt mix I use adds back the missing elements to make it safe. There does seem to be a delay between when exactly that is though! When I put my live rock in around 10 mins after adding the salt, it killed off all the worms that were hiding in the rock! Oh, and obviously distilled wouldn't be great if you have a large tank, since it produces water VERY slowly.

Best way to know if your tap water is good before and or after water conditioners is well obviously look it up or ask your local city maintenance for it... Then just use what's best to get it what you need that with mixed with salt will do the trick. Lucky enough where I live here in, Minnesota. St. Louis Park area the water isn't bad. I and need to in a pinch I use Seachem Prime. For what I need and works out greatly

My well water is pretty high in calcium and alk, but it does have some phosphates in it, so i just run gfo. When I switched to rodi for my topoff, I had to start dosing calcium and alk within the fist week. I quit testing the previous year because it never really swung. I haven't really noticed a difference in my coral growth. Might start dosing my well as if it is kalkwasser again.. sure was easier then dosing.

We have a well, it's been tested for aquarium use many times over the years. The biggest thing we know about it is it's hard. Freshwater angels needed to be acclimated to the hardness. In regards to the salt tanks, the calcium was off the chart.

I would have loved to see just RO water from a local family purified water store included.

I used tap water to cycle my tank. I kept it fish only until I did enough water changes to change all yhe water in the tank twice over. At the time I couldnt afford to use RODI water to fill the tank. I had some really bad algae until I had done a dozen water changes.

Thoughts on using tap in a marco Plante tank? Wouldn't tap benefit the macros?

Housr water has both a sand filter and cannister ceramic filter. Though im curious will topling off decrease ph.

In the 90s we kept discus bred angelfish and had two live rock with fish set ups and ran tap water with nothing added but good ole reef crystals

Would this be the case with store bought distilled water, or since I’m on the coast could I bottle my own salt water ?

Was your well water sample taken after filtration?

Hi: Would have liked to see one of the test groups be one of those under sink carbon/filter setup like for drinking water. How much of the crap does a Britta-like filter take out?

I have a 75 gallon fresh water tank that I have never treated with any chemicals. And all my fish do fine it. Not sure if it’s just a fresh water fish thing or my water is not that chlorinated?

Unrelated to this video, but any update to the aquabiomics testing on the test tanks and the pest stew?

What is the cause of the alk increase? just excess minerals and stuff in the tap water? Asking cause for some reason when mixing salts WITH RODI i always get higher alk then advertised on the bucket for 1,026 salinity. I have recently switched salts to Red Sea and wanted to try the 50/50 mix you had in a video long time ago...mixing at 9,4, in my case it mixed well over 12, last water change i did 1100g blue and 100g black(30l...should be 1185g) and the KH was 9,6. Next water change ill try blue bucket alone, my guess is it will mix around 9,4 which will be ideal, but i am kinda baffled why is my KH always higher. I will see if next batch of salt will be different, might be just this bucket idk. Did ICP on the RODI and it was perfect btw

I had 15 years a 1000l water tank that worked with tap water which I never checked the quality of water, no two part use just tap water . It worked great.but I would probably not take the risk again

Love brs

By next month I'll have gone a full year without ever having used RODI water in my Reef. Every water change I've done has been with rainwater that's collected in a water-tank in my backyard, mixed with a high quality SPS salt called Kirby's premium SPS salt also used since start. I run a hose into my room from that water-tank so I don't need to run buckets around, and can just top up my ATO and mix salt for WC's in my room. It's not necessarily something I'm proud of, it's just I've not really had an extra $550 on hand to buy a boosted RODI unit that I intend to connect to the water-tank. Sometimes I do extra water changes here and there if the Corals look a little mad about something in the water. But other than that I think the worst case scenario for me would be accidentally or unknowingly dumping nitrates and phosphates into my tank from any broken down organics that might make their way into my rain-water-tank, forcing me to do an earlier WC, if there's algae on substrate, it's the indicator I need for a WC. Tank: Waterbox 25G Peninsula Mini Livestock: Clownfish Pair Firefish Goby 4 Trochus Snail from small to big 2 Turbo Snails 3 Stomatella Snails 1 Tropical Astraea Snail 2 Sexy Shrimp Corals: Acropora-Blue Digitata Branching-Type Hammer Euphyllia 2 Chalice varieties Mandarin Fireworx Clove polyps 3 Acans in a garden (could be Micromussa but who knows lol) a Duncan 4 Zoanthid morphs 3 leptoseris morphs a Blastomussa colony that started as a single polyp an Anthelia frag that is quite sentimental to me, I almost lost it one to a nutrient overload. A large green Cynarina A couple fully engulfed GSP frags I recently got a new Blasto single polyp frag and my first Button Scoly which is also a tiny frag. I would consider my tank to be a successful mixed reef without ever having used RODI. I get that it's almost like spinning a revolver and playing roulette. But it's also been relatively manageable for almost an entire year. I haven't ruled out RODI, I would prefer to use it honestly but $$$. My brain sees pretty coral and immediately thinks oh, I have a morph of that, Screw saving! Thanks for ready fellow reefers and BRS team hehe.

I live in the Netherlands and we are known for having the cleanest tapwater in the world. I use tapwater without any extra treatments on both my freshwater and reeftank for over 5 years and both do great.

Nice! I tested my Tap water and grocery story distilled water. My tap water has a phosphate off .65! The grocery store distilled water measured at 0.

The one aspect where I think tap water will potentially hold the largest negative impact is for top-up water and not initial water or even WC's. Reason? Well, that top-up evaporates and you then top it up with more water containing impurities which will slowly increase over time until toxic levels are reached. Just my view.

I use only tap water for my my saltwater fish tank but no corals yet, and fishes are doing good 9 years ago

I use tap for my Cichlids with prime and for my salt i use proper RO from the shop0.25/6

Was that the Turkish Blend TM that you used?

People are happier under good lightning . Have you increased your par in the warehouse ? It was way to dim when I was there . Love your detail ! Look into high efficiency lighting options Coral Dude . It's kinda like lightning a big tank

I didn’t see anything when you said “my investigates over here”, how can I see those results?

I wouldn't do it now but back in the day we did it all the time

I had one home where the city tap water was 40ppm nitrate right out of the tap. OUCH.

Wow that's shocking glad I use RODI unit

Can I just purified drinking water until I can get a rodi system?

I live in san diego California and the water is loaded with dissolved metals amongst other chemicals to counteract it... I occasionally use tap water on my freshwater tank tobtop it off and i dont have issues. When i first made the switch to Salwater after moving here frim Buffalo NY where i nvr heard of buying aquarium water. The tap h2o was good back then and there so i assumed these LFS workers were exaggerating when they all said i needed to buy rodi for my mix and topoff...so i started my system with tap water. I hate testing. I dont do it regularly and just rely on my my tank's appearance to let me know. You should know im naturally riddled with anxiety & can get pretty ocd on stuff like this so i choose to ignore that part in favor of religous weekly 25% H2o changes, running a carcon reactor, a bioball reactor that feeds my skimmer before my sump's refugium. All that to say my water is heavily filtered becsuse i dont want to test. I feel like if i get a bad test result what can i do then and there? Usually nothing unless you have chemicals to counteract it or rodi on hand to do a heavy water change. Im poor and live in an apartment in Downtown San Diego, the nations 2 most epensive city in the country to reside in, and dont have extra money for all these chemicals. I have the eye dropper reef test kit and the few times ive used it i found it terribly hard to perform and then read the results. Maybe im colorblind or something... maybe id like the test srips more? My ultimate goal would be to automate testing and dosing but am far from there. Atm im shopping for lights to replace my dsuny cheap black boxes. Im only replacing because channel 3 blues in one panel are completly burned out and dead fully. as far as functionality goes these dsuny black boxes r all that and more. So my new ones need all that stuff: sunrise/sunset, 4 individually controlled channels, a controller, an app for the smartphone, weather variations, realtime moon functionality...all that Any suggestions$ less than say $350??? I have the standard 55 gallon tank set up as a peninsula w only 1 short side set against the wall rather than the entire "back" of the aquarium. Toughes part is having all my rock work in the middle of the already small 12" wide body to work with...my next tank will be one designed for this...p Kessil a80×2, what would be best for me??? Thanks!!!

Was this tested with the turkey Tropic marine or German tropic marine

I wouldn't use tap but I have used distilled water from Walmart. However, once I switched to RODI the growth of my corals exploded... Your mileage may vary.

I can buy a gallon of distilled water here where I live for 1 euro per gallon, if you have a very small tank for example 20L you don't need much more than that. for larger tanks osmosis is needed since its not cost effective for

What if you ran that tap water through a brita water filter then use the chemical?

What about fluoride? is this not a worry

Can i use rock salt for reef tank

I did it for 2 years on a service tank. Always had random algae, I blame chloramine.

Nice @ 3:38.

What if I'm not trying to keep reef just fish

How about filter water from local drinking shop?

Ya works fine, works good even. As long as you're on a city water supply should be fine.

I use tap water to mix up my saltwater for my reef, 6.8 pH, 0gh, 0kh, no nitrates or phosphate, and I have 15 TDS from the tap, I live in Portland Oregon, I just use prime and mix it's up, my reef is almost a year old with little to no algae issues. I am a newbie to salt but know your water and you might not need to buy an RODI unit.

I don't understand how the same city water from different locations in that close of proximity can have such different readings...?

Do rivers not flow into the ocean

What about distilled water from the grocery store just for top ups?

would have been nice to also get the data on the water before salt was added.

Idk fellas... There is just so much about the other hundreds of different chemicals, elements, etc that we just don't know the long term effects of. I think stuff like this will encourage people to use unsuitable water and cause problems. Is rodi systems REALLY out of range for the average reefer? I don't think so. A 5 stage buddy RO is like $60.

Everybody in the comment understanding everything meanwhile me who still doesn’t know if I can use tap water for my tank

What about trace elements???????????

I hear that if you fill a drum with tap water a leave to stand for 24 to72 hours that the chemicals from the water evaporates and is then safe for use in the tank

Best I can tell all you need do is add some vinegar to drop you alk and you good to go.

Silicate is another issue from tap water

So what is the conclusion now? Yes or no ?

Could be a gamble every time you fill up from the tap unless you test fully every time…..nope.

Why is tap water ok for freshwater and not saltwater

I have well water also don’t see a difference

5:06 "112 potential elements in your tap water"? No, nobody has any risk of having copernicium in their tap water.

So I can use tap hahaha

Screw the fish....I'd be more worried about my drinking water being cancerous.

This test answers nothing meaningful though. What is the difference between 0.05 and 2 ppm of any given chemical? Where do guidelines for what is considered "good" water for a saltwater aquarium come from? I find there is a lot of snake oil being sold when it comes to any hobby. The real test should not just look at abstract numbers. The real test should see what the effect of using dechlorinated tapwater is on an aquarium.

If you have tested your water and know that you can get away with it that's fine. If you haven't, it's like putting the lowest octane pump gas in a race car and wondering why it doesn't run right.

FOWLR. yes. Reef. No.

I think the things you DON'T test for are just as dangerous. Copper, Iron and other heavy metals. Even things like arsenic are deemed "safe" at .01ppm. Personally I don't want anything I don't know about going into the tank so I use RO/DI so I can start from a known 0 and reduce variables.

And non aquarium branded ro water kits do the same for less . Just Branding. So ro water is around a 200 dollars kit now days . Why branding name plates cost more ? Just stop branding. And show test results .

Please don’t mix up PPB and PPM in the same chart without showing the difference. I think it’s best if you are as scientific as possible at all times please.

Short answer: No You must use RODI water.

If you ask this question you should not own a reef tank. Stick to fresh water

I used tap water for my salt tanks in the 1980s.