Detailed mixing station plan - complete parts list

[Kongar]

Hello all,
Here’s my detailed plans with a parts list for a saltwater mixing station project I just completed. It isn’t anything novel, but I thought a shopping list along with some tips and tricks would be appreciated. Basically I built a sturdy stand out of 2x4s and plywood and painted it white. This was put into a small closet next to my fish tank. 2 plastic tanks go on top, plastic bins go underneath for storage (salt, testing kits, hoses, etc). The plumbing accomplishes the following: circulate within either tank, transfer from one tank to another, pump out from either tank through a flexible hose (water change & ato reservoir fillup). Inside the tanks, there are angled outlets to provide a mixing function as well. Obviously the rodi tank has an additional float valve accepting clean rodi.

The hand written plans (I’ll type up the parts list so you don’t have to read my messy handwriting):

The final product:

The inside plumbing (missing the elbow on the inlet)

It comes apart into 2 tanks, and three major pipe sections. It’s pretty easy to break down and move (for cleaning and whatnot)

 

[Kongar]

Tips and Tricks

1. Pay attention to which way the bulkheads go. I installed all four backwards, and they leaked. It’s obvious why they have to go in a certain way - but I didn’t realize my mistake until it was too late. You cannot find bulkheads at your big box stores or local hardware stores, so order extra, and don’t screw them up or your project will be waiting for a shipment.
2. Use clear pvc primer. I did a good job, but I still managed a couple of purple stains I’d rather not have
3. Make sure you can reach the bottom of your tank and all the holes you drill. I was dangerously close to not being able to reach the two holes I had already drilled.
4. Buy extra fittings and unions and pipe - you’ll make mistakes and need more parts.
5. Always make the first pipes coming out of the tanks the same length. The plastic tanks flex, and there’s temptation to measure and cut to different lengths (because the tanks aren’t perfectly symmetrical). Don’t do it - you’ll end up with crooked pipes. Make the parts the same lengths and the tanks will flex into position.
6. DO pay attention to the pump’s offset on the outlet. It’s easy to split measurements in half but you need to consider that not everything splits the middle. Look closely at the vertical pipe on mine and you’ll realize it’s about an inch to the right. That affected the cuts up top and shifted that T to the right.
7. Make the horizontal pipes first, then fit the singular vertical pipe in. It’s impossible to do it the other way around perfectly. It just ends up crooked and while maybe a real plumber can do it - I could not. Do the equal sides of the T first (equally), and then do the singular part that T’s off. Much better results.
8. Read some postings on working with pvc pipe. You need to measure your fittings. You cannot dry fit them as they don’t go all the way in unless they have been melted with cement.
9. I was afraid that iwaki pump would be too much. It’s not too small, but you could absolutely go bigger if you wanted to (I’d say required for larger volumes). I’d say the flow rate could be tripled in these 20 gal tanks before it becomes too splashy.
10. It’s not shown in pictures, but I put an elbow inside the tanks on the bulkheads. They are about 1/4 inch off the bottom and drain the tanks right down to almost nothing. Without that elbow, I’d probably not be able to drain the last 10% of the tank volume. Works good. I didn’t cement these pieces so I could take them in and out to get just the right depth.
11. I cemented everything else using slip fittings. Much better than threads imo. The only threaded pieces are on the pump.
12. I hard piped everything. It looks awesome, but the top piece was really hard to do. If I built another one, I might consider flex hose through uniseals. It wouldn’t look as professional, but would probably take 1/10 the time. I’d have to figure out how to mount the upper valves too.
13. Make sure you have some silicone on hand. My brand new tanks leaked from the factory drain plug. You’d think these things would be tested, but no. I had to reseal those factory plugs.
14. DO leak test your finished product (preferably outside). I’m so glad I did. None of my joints leaked, but I did find out about those factory plugs, it’s how I figured out I installed the bulkheads backwards, and I found a thread I forgot to put Teflon tape on.
15. The b and f couplings work great with that barb fitting and hose. Yes I know they both say male - go read the descriptions. Those are the correct parts that fit with the barbed fitting. The coupling threads directly into the valve female fitting (it’s the only threaded valve part I used).
16. You will need every single part listed. The only bit you may need more of is pipe depending on how tall your tanks are. I used 5 pieces and had one leftover. If your tanks are really tall, you may need some couplings for big runs (although that would have to be some seriously large tanks)
17. You don’t need to use the schedule 80 fittings. I did just to get the grey and red look. You could replace all those parts with white schedule 40 fittings.
18. The cepex ball valves come with both slip and threaded fittings. I’d stick with the slip fittings myself, but if you’re so inclined to use threads…
19. BRS recommends the straight float valve. I think the adjustable one is better. Then you don’t have to be so precise on the drilling. There’s no way that nut is coming undone.
20. Working with pvc is super messy, do it outside on some cardboard on a nice day. I can’t imagine the mess I would have made if I tried to do this in the house.
21. My tanks have a lid that lets air in when pulling a vacuum. They do NOT let air out and the tanks can pressurize. I haven’t figured out what I’m going to do about this. Leave the lids cracked a bit? Drill a little tiny hole? Find a relief valve that works in the opposite direction and install it? If you do a good enough job on the plumbing and sealing it up, this actually can happen.
22. I used a GFCI short extension cord and two of those switched outlet plugs. This makes turning the pump on and off easy. (The other plug is for a heater because I do large % water changes on a small tank)
23. Get a pvc pipe cutter. It was cheap and way easier to make clean precise cuts than with a hacksaw.

 

[Kongar]

Parts List (everything is 3/4)

Parts I bought from BRS:

1. 1 iwaki md-20rt pump
2. 4 slip slip bulkheads
3. 6 cepex ball valves
4. 6 46” red schedule 40 pipe
5. 2 schedule 80 union thread/slip
6. 4 schedule 80 union slip/slip
7. 1 male thread quick connect cam lever coupling “B” style
8. Male thread quick connect cam lever adapter “F” style
9. 1 schedule 80 straight barb x female thread
10. 15feet braided vinyl tubing kuri tec (get as much as you need)
11. 6 schedule 80 90 degree elbow slip/slip
12. 5 schedule 80 tee slip/slip
13. 9 schedule 80 45 degree elbow slip/slip
14. 1 sound dampening pad
15. Rodi cutter
16. Rodi tube clips
17. Rodi under sink water shut off valve

Parts I bought from the hardware store/Amazon:

1. 1 GFCI extension cord
2. 2 outlet switches
3. 1 male extension cord end (for the pump cord)
4. Screws
5. Wood
6. Pvc primer and cement (get clear)
7. Pvc cutter tool
8. Two hole saws for the bulkheads and float valve
9. Lock tight marine silicone
10. Saddle clamp (for the rodi drain)
11. White paint
12. Rodi unit with float valve, check valve, and auto shutoff
13. 2 plastic tanks
14. screws

Stuff I had, and needed:

1. Drill
2. Sandpaper
3. Cardboard box
4. Garden hose and outside area for leak testing
5. Paint brush
6. Drill bits
7. Screwdriver
8. Crescent wrench
9. Pipe wrench
10. Fish tape
11. Latex gloves
12. Tape measure
13. Knife
14. Level
15. Skill saw

 

[Kittypowpow]

Thank you so much for this. I have 2 55 gal brute cants waiting to become a finished station. I was super motivated but then got overwhelmed when it came to getting parts needed and pvc. This is super helpful and much appreciated!

 

[dangles]

Outstanding work. Super clean and professional looking.
Where did you source the tanks? How much were they?

 

[Kongar]

That’s it. Hope this was helpful! If you have questions or want pictures or part numbers, just let me know and I’ll get them for you!

 

[Kongar]

Thank you so much for this. I have 2 55 gal brute cants waiting to become a finished station. I was super motivated but then got overwhelmed when it came to getting parts needed and pvc. This is super helpful and much appreciated!

No problem - glad to help. That’s exactly why I kept track of what I did - it’s easy to find out what to do from prior posts, but it’s entirely a different thing to get all the parts right. My original design was flawed, I bought some wrong stuff, and had to make three trips to the hardware store and one extra order for bulkheads from brs (putting my project on hold for a week). I wanted to publish the finalized list so people could start off with something that works and modify from there.

 

[Kongar]

Outstanding work. Super clean and professional looking.
Where did you source the tanks? How much were they?

I sourced the tanks from Amazon. They were expensive, but I had birthday and Christmas gift cards piling up - so that’s what I spent that $ on. These are the tanks I bought, they are small because I have a small tank and limited space. Most people probably want bigger. I would have gone brute trash can route if I had the space - but I didn’t. These fit in a tiny closet and were spouse approved - so worth the ridiculously high price.

20 gallon overpriced tank

 

[Relyt4]

Where did you get the tanks from? Would love to have a few

 

[Kongar]

Where did you get the tanks from? Would love to have a few

Linked in the post right above your question. (Assuming I did the hyperlink correctly).

I was editing as you were asking! Posting in stereo!

 

[Kongar]

Detailed pictures if anyone is interested-may help you to figure out exactly how the parts go together.

the GFCI extension cord with the outlet switched plugs.

Closer view of the bottom section

closer view of the pump with threaded unions screwed onto it

Fully assembled outside for leak testing

The bulkheads I used. For flat surfaces-don’t install them backwards like me (I was very sad)

The hole saws I used as well as the 90 degree elbows i used to drain the tanks as low as possible

closeup of the bottom bulkhead correctly installed. Used minimal pipe between bulkhead and union.

Closeup of the top bulkhead

being filled for a leak test!

 

[Relyt4]

Linked in the post right above your question. (Assuming I did the hyperlink correctly).

I was editing as you were asking! Posting in stereo!

Ahh yeah, would be perfect for me but I don't think I can bring myself to buy 3 of em lol.

I came across 23 gallon Rubbermaid space saving trash cans today, look to be about same size I think I'm going to pick up a few of those

 

[Kongar]

Ahh yeah, would be perfect for me but I don't think I can bring myself to buy 3 of em lol.

I came across 23 gallon Rubbermaid space saving trash cans today, look to be about same size I think I'm going to pick up a few of those

I saw some links to discount farm tank places and they weren’t as pricey. I believe my tanks are meant for RVs water storage for showers and whatnot. So they have a strange footprint, screws, and other weird stuff driving the price up. See originally they weren’t going to go in the closet but rather in the bathroom on the side of the vanity sink. So I overpaid for very specific sized tanks. Then I decided to build this. Look around and you’ll find cheaper options I’m sure (but probably nowhere close to brute prices). These white tanks are not cheap :/

 

[Aquaplumb]

Good work, as a plumber I love seeing good work man ship on tank related tasks

 

[Kongar]

Good work, as a plumber I love seeing good work man ship on tank related tasks

You just made my night. I’m pretty handy with a lot of things - but plumbing is not one of them. I’ve screwed up so many plumbing jobs…. It’s just not my thing. That said, I think this one came out alright. But man, it took me forever!

 

[Kongar]

Ah, one more tip I meant to say. That sound dampening pad - it actually serves two purposes. It just so happens to lift the pump the exact amount off the ground you need to line up with the bulkheads. You can’t put the bulkheads super low because there’s a curve at the bottom and they have a large lip around the gasket. You don’t need that overpriced sound dampening pad, but you’ll need something to lift that pump up. That stupid foam pad just happens to work perfectly.

 

[aaron186]

How do you handle the back siphon from the salt water container to the RO when you turn off the pump?

 

[Kongar]

How do you handle the back siphon from the salt water container to the RO when you turn off the pump?

I was going to post an update because this is a “mistake” I didn’t anticipate. And it’s not limited to just siphoning. However, they all have easy workarounds - essentially being deliberate about closing valves in the correct order and keeping them closed.

Problem #1
If you open both bottom valves - the two tanks will equalize water levels. Solution: don’t ever open both bottom valves at the same time.

Problem #2
If the top line is full of water AND the return tubing is blow the water line - it siphons. This can happen through the pump, or out the flex hose. This continues until the water level in the tank drops below your return lines and breaks the siphon. Solution: keep the valves shut.

More specifically, this doesn’t become an issue under normal use so just be conscious of the siphon effect. When transferring rodi to the salt tank, the salt tank is mostly empty, and I’ve dropped the water level in the rodi tank below the siphon break point. However it can back flow from the full salt water tank through the pump and into the base of the rodi tank. So I just close the bottom valve of the rodi tank and open the bottom valve of the salt tank immediately going into recirculating mode. This dead heads the pump for a split second but I don’t think that’ll cause any long term issues.

The other time it’s an issue is when pumping from either tank through the flex hose. This happens like 6 times to every 1 time when making salt water (because you make so much more water than you use each time, and your rodi tank always fills up after you fill your ato resorvoir. You can just close off a valve, deadhead the pump for a sec, and flick the switch to turn off the pump (it doesn’t flow backwards through these ball valves - they seal pretty tight). But I’ve actually figured out a better solution. Assume you’ve got the valves such that you’re filling the ato or the water in the tank. When doing this I start by recirculating the water in the tank I want to fill from. Then without closing any valves - I open the valve to the flex hose. This generates almost no flow through the flex hose. Then I close one of the return valves - I use the vertical center line valve just above the flex hose valve. Water flows through the flex hose fast. When I’m close to done filling, I fully open the return valve and throttle closed the flex hose valve. This slows the flow significantly (bonus, I get exactly the level I want without overfill). When full, I completely close the flex valve and leave the system in recirculating mode. Now see problem #3

Problem #3
I didn’t plan on their being so much volume in that flex hose. When I’m done filling, I’ve got to dump all that into a bucket which is a messy operation. What’s easier is to do what I described above where I’ve got a full flex hose and a system in recirculating mode on the tank I was filling from. Now I turn the pump off and raise the free end of the flex hose up over my head (which is higher than the water level in the tanks - even when full). Then I open the flex hose valve again and the water will flow backwards into the tank it came from. My flex hose is now almost empty. (there might be a little bit left only if the water level is higher than that flex hose ball valve - easy enough to catch with a bucket underneath when disconnecting the flex hose with the quick connect fitting).

So in the end, this “mistake” is almost an advantage. Having the ability to back flow is an easy way to manage the water in the flex hose. The disadvantage however, is that if you’re not careful and you put the valves in the wrong position - you could very easily cross flow between your rodi and salt tanks, screwing up both.

I’ve actually gone so far as to think about cutting the pipes and adding some check valves. But in the end I decided I like it the way it is because of the flex hose water management. I just can’t let others use it unless they really understand how it works (for example my wife or kids).

Little bit of a novel - but hopefully that helps. The siphoning aspect isn’t talked about at all and it did catch me by surprise (but it’s ok, maybe that’s why it’s not discussed much)

 

[aaron186]

I was going to post an update because this is a “mistake” I didn’t anticipate. And it’s not limited to just siphoning. However, they all have easy workarounds - essentially being deliberate about closing valves in the correct order and keeping them closed.

Problem #1
If you open both bottom valves - the two tanks will equalize water levels. Solution: don’t ever open both bottom valves at the same time.

Problem #2
If the top line is full of water AND the return tubing is blow the water line - it siphons. This can happen through the pump, or out the flex hose. This continues until the water level in the tank drops below your return lines and breaks the siphon. Solution: keep the valves shut.

More specifically, this doesn’t become an issue under normal use so just be conscious of the siphon effect. When transferring rodi to the salt tank, the salt tank is mostly empty, and I’ve dropped the water level in the rodi tank below the siphon break point. However it can back flow from the full salt water tank through the pump and into the base of the rodi tank. So I just close the bottom valve of the rodi tank and open the bottom valve of the salt tank immediately going into recirculating mode. This dead heads the pump for a split second but I don’t think that’ll cause any long term issues.

The other time it’s an issue is when pumping from either tank through the flex hose. This happens like 6 times to every 1 time when making salt water (because you make so much more water than you use each time, and your rodi tank always fills up after you fill your ato resorvoir. You can just close off a valve, deadhead the pump for a sec, and flick the switch to turn off the pump (it doesn’t flow backwards through these ball valves - they seal pretty tight). But I’ve actually figured out a better solution. Assume you’ve got the valves such that you’re filling the ato or the water in the tank. When doing this I start by recirculating the water in the tank I want to fill from. Then without closing any valves - I open the valve to the flex hose. This generates almost no flow through the flex hose. Then I close one of the return valves - I use the vertical center line valve just above the flex hose valve. Water flows through the flex hose fast. When I’m close to done filling, I fully open the return valve and throttle closed the flex hose valve. This slows the flow significantly (bonus, I get exactly the level I want without overfill). When full, I completely close the flex valve and leave the system in recirculating mode. Now see problem #3

Problem #3
I didn’t plan on their being so much volume in that flex hose. When I’m done filling, I’ve got to dump all that into a bucket which is a messy operation. What’s easier is to do what I described above where I’ve got a full flex hose and a system in recirculating mode on the tank I was filling from. Now I turn the pump off and raise the free end of the flex hose up over my head (which is higher than the water level in the tanks - even when full). Then I open the flex hose valve again and the water will flow backwards into the tank it came from. My flex hose is now almost empty. (there might be a little bit left only if the water level is higher than that flex hose ball valve - easy enough to catch with a bucket underneath when disconnecting the flex hose with the quick connect fitting).

So in the end, this “mistake” is almost an advantage. Having the ability to back flow is an easy way to manage the water in the flex hose. The disadvantage however, is that if you’re not careful and you put the valves in the wrong position - you could very easily cross flow between your rodi and salt tanks, screwing up both.

I’ve actually gone so far as to think about cutting the pipes and adding some check valves. But in the end I decided I like it the way it is because of the flex hose water management. I just can’t let others use it unless they really understand how it works (for example my wife or kids).

Little bit of a novel - but hopefully that helps. The siphoning aspect isn’t talked about at all and it did catch me by surprise (but it’s ok, maybe that’s why it’s not discussed much)

Thanks. I have a very similar build but with brute cans and I’m using an extra Varios return pump. The issue I’m having is when my pump goes dry it shuts off. I have the salt bin plumbed with a return pipe going to the bottom of the bin to assist with mixing. So when that pump shuts off, if I’m not there to catch it immediately, it back siphons. I don’t really want to buy a new pump. I’m wondering if I should just cut the return line above the water so it can’t siphon. Not sure how that will do with mixing. What do you think?

 

[Kongar]

Now for a different issue with the design besides siphoning. Drainage. I really wish I had put a low point drain on the bottom lines. It’s not a lot, but there’s a little bit of fluid that gets trapped between the flex hose valve, through the pump, and T’d to both bottom valves. That ends up being some mix of salt water and rodi. If I’m switching (say I just filled my tank with salt water and now want to use rodi), I have to flow some into a bucket to clean it out. It would have been much more convenient if I put in a small low point drain there…

So if you build this - consider adding that. Otherwise it’s been working great for me. My water changes have become non events. I time myself and it usually takes 10 minutes now (mostly because I’m doing other things). Love this mixing station!