DIY auto water change

[Matth22]

So after finally getting the hang of keeping plants alive 😂 (it’s only been 4 years) I am now building my office aquarium, which is around 350 litres, sitting on a 2x4 over engineered stand sandwiched between a pair of ikea pax units, with a tall larder unit running horizontally across the width as a bookshelf and for somewhere to hang the ONF flat one + light I’ve purchased for the job

Part of the reason I’ve had trouble growing plants is the hard water in my area. I’ve resolved this by doing a 50/50 cut with tap and RO water.

RO has been coming from a 3 stage unit I’ve had sat outside and is labour intensive for my current 160lt tank back and forth with buckets. Plus during the recent cold snap it froze over and cracked a couple of the filter housings.

I’ve purchased in its place a 600gpd, tankless under sink unit which I plan to install under the kitchen sink and use for drinking as well as aquarium use - I can run some RO pipe from under the sink and through the wall my aquarium will sit against no problem and have bought a float valve which has top offs sorted!

Question 1 - I want to use pure RO for top offs but will need to remineralise for water changes. Can I mix remineraliser directly into the tank during the water change?

I’m then thinking of setting up a T joint in the inlet pipe between the inlet and filter with a valve so I can open it and use gravity to empty water directly into the kitchen waste

Question 2 - any obvious reason this wouldn’t work?

In progress build picture attached - the tank is the dimensions of the 2x4 stand if anyone is worried about the overhang - that’s for pipework and will be covered to the height of the tank 😉

 

[Zeus.]

but will need to remineralise for water changes.

Yes, we have a remineralizing section in the IFC Calculator to keep cost down for DIY remineralizing agents /salts

Can I mix remineraliser directly into the tank during the water change?

Ideally, no, best done before hand and brought to temp, but as long as water temps are close it should be an issue IMO and add salts as it fills.

thinking of setting up a T joint in the inlet pipe between the inlet and filter with a valve so I can open it and use gravity to empty water directly into the kitchen waste

Had something similar on 500l tank, makes WC easier and the less hoses involve less chance of spillage

 

[Matth22]

Yes, we have a remineralizing section in the IFC Calculator to keep cost down for DIY remineralizing agents /salts

Ideally, no, best done before hand and brought to temp, but as long as water temps are close it should be an issue IMO and add salts as it fills.

The other thing I was considering is fitting an inline remineralisation filter that are designed for drinking water, but I’m not sure how consistent that will be.

Had something similar on 500l tank, makes WC easier and the less hoses involve less chance of spillage

great! That sorts the draining down part of the process. Thanks for your feedback

 

[dw1305]

Hi all,

I’ve resolved this by doing a 50/50 cut with tap and RO water.

You can <"just use your tap water"> to add calcium (Ca) (dGH) and (bicarbonates) dKH, you are going to add magnesium (Mg) with your fertiliser addition. You don't need to remineralize your RO, the tap water is already doing it.

cheers Darrel

 

[Matth22]

Hi all,

You can <"just use your tap water"> to add calcium (Ca) (dGH) and (bicarbonates) dKH, you are going to add magnesium (Mg) with your fertiliser addition. You don't need to remineralize your RO, the tap water is already doing it.

cheers Darrel

Thanks Darrel.

Issue is, i hadn't really planned on running a tap water feed to the back of the tank. Another option i've been thinking about it T'ing the RO feed off and having one feed for auto top off, and another to feed a water tank in the void under the tank (filter/co2/other components going in left side of the pax units) and then remineralising in there before pumping into the tank itself after the water change - this solves both the remineralising and the very good point Zeus made about temperature given its a tankless RO system.

If i go down this route, i'm guessing i'd need some water movement in the storage tank?

 

[Matth22]

Yes, we have a remineralizing section in the IFC Calculator to keep cost down for DIY remineralizing agents /salts

BTW, the calculator is awesome! I've not delved into DIY ferts yet (not much of a science brain) but this looks like something that might give me some confidence to try!

 

[Zeus.]

BTW, the calculator is awesome! I've not delved into DIY ferts yet (not much of a science brain) but this looks like something that might give me some confidence to try!

Thank you 🙂, it takes a bit of getting use to, but if you have used Excel in past it should be a easy once you get use to it, best used on a PC/laptop IMO

 

[dw1305]

Hi all,

.. the calculator is awesome! I've not delved into DIY ferts yet (not much of a science brain) but this looks like something that might give me some confidence to try!

They have done a really good job with it.

Thanks Darrel.

Issue is, i hadn't really planned on running a tap water feed to the back of the tank.

I don't think you need to. Just add ~10 litres of tap occasionally. You can use a conductivity meter to give you a <"Goldilocks zone" conductivity datum>", or you can the <"snail-shell"> Index.

... Then remineralising in there before pumping into the tank itself after the water change this solves both the remineralising

This is the bit I don't quite get, are you using any tap water at all? If you are? That is your remineraliser and you don't need to add any salts.

If i go down this route, i'm guessing i'd need some water movement in the storage tank?

It would help, but it isn't strictly necessary, an air pump would do.

Cheers Darrel

 

[Matth22]

This is the bit I don't quite get, are you using any tap water at all? If you are? That is your remineraliser and you don't need to add any salts

No tap water at all. I want to run an RO line from the kitchen to the back of the tank and use a float valve to top off/refill. The temperature of the RO feed is what’s got me onto the storage tank idea.

Ideally I don’t want to run a mains water feed to the back of the tank and I’m trying to create a hose less/as close to automated solution as I possible can.

Hopefully that makes a bit more sense now? 😂

 

[bazz]

I'm not sure how familiar you are with RO but you will need auto shut off valves to work in conjunction with the float valves.

 

[Matth22]

I'm not sure how familiar you are with RO but you will need auto shut off valves to work in conjunction with the float valves.

Thanks!

Is this needed for a tankless RO system though? Will the float valve on its own not stop the demand for water?

Link to the system I’ve purchased

600gpd Tankless Reverse Osmosis RO Unit With Faucet

Our Tankless 600GPD Compact 5-Stage Filtration Reverse Osmosis Unit is an excellent solution for pure, clean water directly from your kitchen tap. Designed with multi-stage filtration technology and compact convenience in mind, this system brings you unparalleled filtration power without the...

www.finest-filters.co.uk

The plan is for a T’d connection out of the RO unit, with one feed going to a filter tap in the kitchen, and another going to the back of the tank. In my head, the float valve would work in the same way as turning the filter tap on/off.

My brain has been searching for solutions and I’ve come up with another couple of options that might work -

1) using an inline instant water heater on the RO feed, still filling directly into the tank. At this point I still need to work out how I’m remineralising it. Not against running a mains feed to the tank, but then there’s the question of how I control the temp and tds of the combined RO and mains feeds
2) using the RO line to fill a storage tank under the aquarium and allow the water to reach room temperature. While this isn’t an exact match it’s what I do now in buckets and doesn’t seem to cause any issues. I don’t have enough space to store a full 50% water change so I’d look to use a few buckets of tap water to remineralise.
3) left field option - what about a continuous water change approach? I plan to dose EI, so im not sure this would work? If it did, I could perhaps add some crushed coral to the filter

What seemed like a stroke of genius initially is throwing up a lot of hurdles!

 

[bazz]

Is this needed for a tankless RO system though? Will the float valve on its own not stop the demand for water?

The unit can possibly continue to run when using a float valve (although I'm not familiar with this particular system, just the generic RO type). When the float valve is closed the small amount of pressure that builds up on the low pressure side will shut the valve off on the high pressure side if that makes sense. Worth looking into along with the use of a check valve.

 

[dw1305]

Hi all,

No tap water at all.

OK, that makes sense.

Just add ~10 litres of tap occasionally. You can use a conductivity meter to give you a <"Goldilocks zone" conductivity datum>", or you can the <"snail-shell"> Index.

You can still do that, or add your own salts via the IFC spreadsheet. Have a look at @Roland 's <"Softwater tank">.

My 70l tank,gh5/6 ,kh1,K15ppm,No3 5/10ppm,po4 0.20ppm,tropica soil substrate,Sky light 60 light,co2 40ppm,fertilization -tropica green+ Aqua rebell micro special flowgrow

cheers Darrel

 

[Matth22]

Hi all,

OK, that makes sense.

You can still do that, or add your own salts via the IFC spreadsheet. Have a look at @Roland 's <"Softwater tank">.


cheers Darrel

Awesome. Thanks for the advice!

Adding a bucket or two of tap water seems like a good idea 👍🏼